Flat display device and method for making the same

ABSTRACT

A flat-type display comprising a first panel AP and a second panel CP which are bonded to each other in their circumferential portions and having a space between the first panel AP and the second panel CP, the space being in a vacuum state, a spacer being disposed between a first panel effective field and a second panel effective field that work as a display portion, said spacer being fixed to the first panel effective field and/or the second panel effective field with a low-melting-point metal material layers  33 A and  33 B.

TECHNICAL FIELD

The present invention relates to a flat-type display such as, forexample, a cold cathode field emission display, and a manufacturingmethod thereof.

BACKGROUND ART

In the fields of displays for use in television receivers andinformation terminals, studies have been made for replacingconventionally mainstream cathode ray tubes (CRT) with flat-paneldisplays which are to comply with demands for a decrease in thickness, adecrease in weight, a larger screen and a high fineness. Such flat paneldisplays include a liquid crystal display (LCD), an electroluminescencedisplay (ELD), a plasma display panel (PDP) and a cold cathode fieldemission display (FED). Of these, a liquid crystal display is widelyused as a display for an information terminal. For applying the liquidcrystal display to a floor-type television receiver, however, it stillhas problems to be solved concerning a higher brightness and an increasein size. In contrast, a cold cathode field emission display uses coldcathode field emission devices (to be sometimes referred to as “fieldemission device” hereinafter) capable of emitting electrons from a solidinto a vacuum on the basis of a quantum tunnel effect without relying onthermal excitation, and it is of great interest from the viewpoints of ahigh brightness and a low power consumption.

FIG. 22 shows a schematic partial end view of a cold cathode fieldemission display having field emission devices (to be sometimes referredto as “display” hereinafter). The field emission device shown in FIG. 22is a so-called Spindt-type field emission device having a conicalelectron-emitting portion. Such a field emission device comprises acathode electrode 11 formed on a supporting member 10 formed of a glasssubstrate, an insulating layer 12 formed on the supporting member 10 andthe cathode electrode 11, a gate electrode 13 formed on the insulatinglayer 12, a first opening portion 14A formed through the gate electrode13 and a second opening portion 14B formed through the insulating layer12, and a conical electron-emitting portion 15 formed on the cathodeelectrode 11 positioned in the bottom portion of the second openingportion 14B. Generally, the cathode electrode 11 and the gate electrode13 are formed in the form of a stripe, each stripe being oriented indirections in which the projection images of these two electrodes crosseach other at right angles. Generally, a plurality of field emissiondevices are arranged in a region (corresponding to one pixel, and theregion will be called an “overlap region” or an “electron-emittingregion EA” hereinafter) where the projection images of the above twoelectrodes overlap. Further, generally, such electron-emitting regionsEA are arranged in the form of a two-dimensional matrix within aneffective field (which works as an actual display portion) of thecathode panel CP.

The anode panel AP comprises, for example, a substratum 20, a phosphorlayer 23 (a phosphor layer 23R that emits light in red, a phosphor layer23G that emits light in green and a phosphor layer 23B that emits lightin blue in a case of a color display) which is formed on the substratum20 and has a predetermined pattern, and an anode electrode 24 formedthereon. The anode electrode 24 has not only a function such as areflecting film which reflects an emitted light from the phosphor layer23, but also a function such as a reflecting film which reflectselectrons recoiled from the phosphor layer 23 or secondary electronsemitted from the phosphor layer 23, and a function for preventingelectrostatic charge of the phosphor layer 23.

Each pixel is constituted of an electron emitting region EA on thecathode panel side and a phosphor layer 23 on the anode panel sidefacing a group of these field emission devices. In the effective field,these pixels are arranged in the order of hundreds of thousands toseveral millions. A partition wall 322 is formed on the substratum 20between one phosphor layer 23 and another phosphor layer 23. FIGS. 3 to5 schematically show layouts of the partition wall 322, the spacer 331and phosphor layer 23. Further, a light-absorbing layer (called “blackmatrix” as well) 21 is formed on the substratum 20 between one phosphorlayer 23 and another phosphor layer 23. Part of the partition wall 322works as a spacer holder 330. While FIGS. 3 to 5 show the partition wall22, the spacer holder 30 and the spacer 31, the partition wall 22, thespacer holder 30 and the spacer 31 shall be read as the partition wall322, the spacer holder 330 and the spacer 331.

A plurality of separation walls 322 prevent the occurrence of aso-called optical crosstalk (color mixing) that is caused when electronsrecoiling from the phosphor layer 23 or secondary electrons emitted fromthe phosphor layer 23 enter another phosphor layer, or prevent thecollision of electrons with another phosphor layer when electronsrecoiling from the phosphor layer 23 or secondary electrons emitted fromthe phosphor layer 23 enter another phosphor layer 23 over theseparation wall.

The anode panel AP and the cathode panel CP are arranged such that theelectron-emitting regions and the phosphor layers 23 are opposed to eachother, and the anode panel AP and the cathode panel CP are bonded toeach other in their circumferential portions through a frame (notshown), whereby the display is produced. In an ineffective field whichsurrounds the effective field and where a peripheral circuit forselecting pixels is provided, a through-hole (not shown) for vacuumingis provided, and a tip tube (not shown) is connected to the through-holeand sealed after vacuuming. That is, a space surrounded by the anodepanel AP, the cathode panel CP and the frame is in a vacuum state.

When the spacer 331 is not provided between the anode panel AP and thecathode panel CP, therefore, the display is damaged under and due toatmospheric pressure.

Therefore, in an image display or a flat-type display disclosed inJP-A-7-262939 or JP-A-2000-156181, a positioning member or a supportingmember is formed on a black matrix formed on a front panel or asubstrate, a brace member or a spacer is embedded between a pair of thepositioning members or between the supporting members.

Further, in an image display disclosed in JP-A-2000-57979, a spacer anda cathode substrate are fixed to each other with an ultraviolet raycuring adhesive or an inorganic adhesive. Further, JP-A-10-199451discloses a display in which a panel body and a spacer portion areintegrated.

Meanwhile, the spacer 331 generally has a height of 1 to 2 mm andthickness of 0.05 to 0.1 mm. During the process of producing thedisplay, therefore, it is difficult to keep the spacer 331self-supported, and it is required to hold the spacer 331 between a pairof the spacer holders 330. For embedding the spacer 331 reliably betweena pair of the spacer holders 330, the distance between the pair of thespacer holders 330 is required to be greater than the thickness of thespacer 331. When the distance between the pair of the spacer holders 330is too broad as compared with the thickness of the spacer 331, however,the spacer 331 comes to tilt in the process of producing a display afterthe spacer 331 is embedded between the pair of spacers 330, and when theanode panel AP and the cathode panel CP are assembled, there is caused aproblem that the spacer 331 and the spacer holder 330 are broken.Particularly, when the display is increased in size, the number of thespacers increases, and it is more difficult to hold the spacersperpendicularly.

In the image display disclosed in JP-A-2000-57979, the spacer and thecathode substrate are fixed to each other with an ultraviolet raycurable adhesive or an inorganic adhesive, so that the tilting of thespacer 331 can be prevented. However, there are remaining problems onthe release of a gas from the adhesive and thermal deterioration of theadhesive. When a gas is released from the adhesive, the vacuum degreeinside the image display may be degraded. When some gas is presentinside the image display, for example, a cold cathode field emissiondisplay has problem that since fine electron emitting portions aresputtered with ions generated by the gas, the electron emissionefficiency is changed, or that since electron emitting portions aredamaged, the lifetime of the image display is decreased.

In the display disclosed in JP-A-10-199451, there is caused a problemwherein because the process for producing an integrated structure of apanel body and a spacer portion is difficult, the production cost isincreased.

JP-A-2000-200543 discloses a technique of bonding circumferentialportions of an anode panel and a cathode panel to each other with alow-melting metal. However, it describes nothing concerning the fixingof any spacer.

It is therefore an object of the present invention to provide aflat-type display having a structure that can avoid the occurrence ofthe problem in which the spacer tilts in the process of producing theflat-type display and that is free of the problems of the release of agas from a material fixing the spacer and the thermal deterioration of amaterial fixing the spacer, and a method for producing the same.

DISCLOSURE OF THE INVENTION

The flat-type display of the present invention for achieving the aboveobject is a flat-type display comprising a first panel and a secondpanel which are bonded to each other in their circumferential portionsand having a space between the first panel and the second panel, thespace being in a vacuum state,

-   -   a spacer being disposed between a first panel effective field        and a second panel effective field that work as a display        portion,    -   said spacer being fixed to the first panel effective field        and/or the second panel effective field with a low-melting-point        metal material layer.

That is, the flat-type display of the present invention specificallyincludes

(1) a constitution in which the low-melting-point metal material layeris present between the spacer and that portion of the first panel whichconstitutes the first panel effective field (to be referred to as“flat-type display according to a first-A constitution” forconvenience),

(2) a constitution in which the low-melting-point metal material layeris present between the spacer and that portion of the second panel whichconstitutes the second panel effective field (to be referred to as“flat-type display according to a first-B constitution” forconvenience), and

(3) a constitution in which the low-melting-point metal material layeris present between the spacer and that portion of the first panel whichconstitutes the first panel effective field and the low-melting-pointmetal material layer (second low-melting-point metal material layer) isalso present between the spacer and that portion of the second panelwhich constitutes the second panel effective field (to be referred to as“flat-type display according to a first-C constitution” forconvenience).

The first panel effective field and the second panel effective fieldrepresent a field that works as the actual display portion of the firstpanel and a field that works as the actual display portion of the secondpanel, as will be used in this sense hereinafter. Ineffective fields arepositioned outside the first panel effective field and the second paneleffective field. That is, the ineffective fields surround the firstpanel effective field and the second panel effective field.

The flat-type display of the present invention may have a constitutionin which a plurality of spacer holders for temporarily holding thespacer are formed in the first panel effective field and/or the secondpanel effective field. The above constitution will be referred to as“flat-type display according to the second constitution” forconvenience. It is required to arrange the spacer on the first paneleffective field and/or the second panel effective field before thespacer is fixed to the first panel effective field and/or the secondpanel effective field. When the above spacer holders are provided, thefalling or tilting of the spacer can be reliably prevented in a stepfollowing the arrangement (temporarily holding) of the spacer on thefirst panel effective field and/or the second panel effective field. Amore specific layout, etc., of the spacer holders will be describedlater.

Table 1 shows portions where the spacer holders are to be formed whenthe second constitution is applied to the first-A, first-B and first-Cconstitutions. In Table 1 and Table 2 to be described later, “◯” meansthat a spacer holder is provided, and “X” means that no spacer holder isprovided. TABLE 1 position of low-melting- point metal material layerposition of spacer holder between between to be formed in Second firstpanel second panel Constitution Case and spacer and spacer first panelsecond panel 1 First-A ◯ X X X 2 Constitution ◯ X 3 ◯ ◯ 4 X ◯ 11 First-BX ◯ X X 12 Constitution ◯ X 13 ◯ ◯ 14 X ◯ 21 First-C ◯ ◯ X X 22Constitution ◯ X 23 ◯ ◯ 24 X ◯

The method for manufacturing a flat-type display, provided according toa first aspect of the present invention for achieving the above object,is a method for manufacturing a flat-type display comprising a firstpanel and a second panel which are bonded to each other in theircircumferential portions and having a space between the first panel andthe second panel, the space being in a vacuum state, a spacer beingdisposed between a first panel effective field and a second paneleffective field that work as a display portion, the method comprising;

(A) arranging a spacer with a low-melting-point metal material layerformed on one top surface thereof, on the first panel effective field,then,

(B) heating the low-melting-point metal material layer to melt the sameand thereby fixing said spacer to the first panel effective field, andthen,

(C) placing the second panel on the other top surface of the spacer,bonding the first panel and the second panel to each other in theircircumferential portions, and vacuuming the space sandwiched between thefirst panel and the second panel.

The method for manufacturing a flat-type display, provided according tothe first aspect of the present invention, may have a constitution inwhich a second low-melting-point metal material layer is formed on theother top surface of the above spacer, the second low-melting-pointmetal material layer is melted together when the first panel and thesecond panel are bonded to each other in their circumferential portionsin the above step (C), and the above spacer is thereby fixed to thesecond panel effective field. This constitution will be referred to as“method for manufacturing a flat-type display, provided according to thefirst-A aspect of the present invention” for convenience.

The method for manufacturing a flat-type display, provided according tothe first aspect of the present invention including the first-A aspectof the present invention, may also have a constitution in which aplurality of spacer holders for temporarily holding the spacer areformed in the first panel effective field and/or the second paneleffective field. This constitution will be referred to as “method formanufacturing a flat-type display, provided according to the first-Baspect of the present invention” for convenience. More specificarrangements of the spacer holders will be described later.

The method for manufacturing a flat-type display, provided according toa second aspect of the present invention, is a method for manufacturinga flat-type display comprising a first panel and a second panel whichare bonded to each other in their circumferential portions and having aspace between the first panel and the second panel, the space being in avacuum state, a spacer being disposed between a first panel effectivefield and a second panel effective field that work as a display portion,the method comprising;

(A) providing the first panel in which a low-melting-point metalmaterial layer is formed in a portion where the spacer is to be fixed inthe first panel effective field,

(B) arranging the spacer on said low-melting-point metal material layer,heating the low-melting-point metal material layer to melt the same, andthereby fixing said spacer to the first panel effective field, and then,

(C) placing the second panel on the other top surface of the spacer,bonding the first panel and the second panel in their circumferentialportions and vacuuming the space sandwiched between the first panel andthe second panel.

The method for manufacturing a flat-type display, provided according tothe second aspect of the present invention, may have a constitution inwhich a second low-melting-point metal material layer is formed on aportion where the spacer is to be fixed in the second panel effectivefield, the second low-melting-point metal material layer is melted whenthe first panel and the second panel are bonded in their circumferentialportions in the above step (C), and thereby the spacer is fixed to thesecond panel effective field. This constitution will be referred to as“method for manufacturing a flat-type display, provided according to thesecond-A aspect of the present invention” for convenience.

The method for manufacturing a flat-type display, provided according tothe second aspect of the present invention including the second-A aspectof the present invention, may also have a constitution in which aplurality of spacer holders for temporarily holding the spacer areformed in the first panel effective field and/or the second paneleffective field. This constitution will be referred to as “method formanufacturing a flat-type display, provided according to the second-Baspect of the present invention” for convenience. More specificarrangements of the spacer holders will be described later.

Table 2 shows portions where the spacer holders are to be formed whenthe method for manufacturing a flat-type display, provided according tothe first-B aspect of the present invention, is applied to the methodfor manufacturing a flat-type display, provided according to the firstaspect and the first-A aspect of the present invention and when themethod for manufacturing a flat-type display, provided according to thesecond-B aspect of the present invention, is applied to the method formanufacturing a flat-type display, provided according to the secondaspect and the second-A aspect of the present invention. TABLE 2 [Methodfor manufacturing A-flat-type display] position of low-melting- pointmetal material layer between between position of spacer holder firstpanel second panel to be formed Case and spacer and spacer first panelsecond panel 31 First Aspect ◯ X X X 32 ◯ X First-B Aspect 33 ◯ ◯First-B Aspect 34 X ◯ First-B Aspect 41 First-A Aspect ◯ ◯ X X 42 ◯ XFirst-B Aspect 43 ◯ ◯ First-B Aspect 44 X ◯ First-B Aspect 51 SecondAspect ◯ X X X 52 ◯ X Second-B Aspect 53 ◯ ◯ Second-B Aspect 54 X ◯Second-B Aspect 61 Second-A ◯ ◯ X X 62 Aspect ◯ X Second-B Aspect 63 ◯ ◯Second-B Aspect 64 X ◯ Second-B Aspect

In the flat-type display of the present invention including theflat-type display according to any one of the first-A to first-Cconstitutions and the second constitutions, the method for manufacturinga flat-type display according to the first aspect of the presentinvention including the first-A and first-B aspects of the presentinvention, or the method for manufacturing a flat-type display accordingto the second aspect of the present invention including the second-A andsecond-B aspects of the present invention (these will be sometimesreferred to as “the present invention” hereinafter), the spacer ispreferably formed of ceramics. Specific examples of the ceramics includealumina, mullite, barium titanate, lead titanate zirconate, zirconia,cordierite, barium borosilicate, iron silicate, glass ceramic material,and a mixture of any one these with titanium oxide, chromium oxide, ironoxide, vanadium oxide or nickel oxide. When these are used, a so-calledgreen sheet is formed, the green sheet is fired and the thus-obtainedgreen sheet fired product is cut, whereby the spacer can be produced.Alternatively, the spacer can be formed of glass such as alkali glasscontaining 25% of iron oxide. A metal layer, a metal alloy layer or aresistance layer may be formed on part of the side surfaces of thespacer. A conductive material layer made of a metal or a metal alloy maybe formed so as to cover the top surface of the spacer. When the aboveconstitution is employed, there is removed a voltage difference betweenthe spacer constituted of an insulating material and elementsconstituting the first or second panel, and there can be inhibited theoccurrence of a discharge between the spacer constituted of aninsulating material and elements constituting the first or second panel.When the spacer is cut with an imaginary plane perpendicular to thelongitudinal direction thereof, the spacer generally has across-sectional form of a long and narrow rectangle.

The height, thickness and length of the spacer can be determined on thebasis of the specification, etc., of the flat-type display, and forexample, the thickness of the spacer is 20 μm to 200 μm, for example, 50μm, and the height is 1 mm to 2 mm. The size of the spacer holders andthe distance between the spacer holders can be determined on the basisof the specification, etc., of the flat-type display as well, and forexample, the height of the spacer holders is 20 to 100 μm, and thethickness thereof is 10 to 50 μm. The distance between a pair of thespacer holders for holding the spacer can be determined on the basis ofthe thickness, formation accuracy and processing accuracy of the spacerand the processing accuracy and formation accuracy of the spacerholders.

In the present invention, the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of frit glass, or there can be employed a constitution inwhich the first panel and the second panel are bonded to each other intheir circumferential portions through a bonding layer made of fritglass. The above frit glass is a high-viscosity paste-like materialobtained by dispersing glass fine particles in an organic binder, andthe high-viscosity paste-like material is applied in a predeterminedpattern and then fired to remove the organic binder, whereby a solidbonding layer is formed.

Alternatively, in the present invention, the first panel and the secondpanel are bonded to each other in their circumferential portions througha bonding layer made of a low-melting-point metal material, or there canbe employed a constitution in which the first panel and the second panelare bonded to each other in their circumferential portions through abonding layer made of a low-melting-point metal material.

In the flat-type display of the present invention including theflat-type display according to the second constitution, there can beemployed a constitution in which the flat-type display is a cold cathodefield emission display, the first panel is an anode panel in which ananode electrode and a phosphor layer are formed, and the second panel isa cathode panel in which a plurality of cold cathode field emissiondevices are formed.

In the method for manufacturing a flat-type display, provided accordingto the first aspect of the present invention including the first-A andfirst-B aspects of the present invention, or the method formanufacturing a flat-type display, provided according to the secondaspect of the present invention including the second-A and second-Baspects of the present invention, there can be employed a constitutionin which

(a) the flat-type display is a cold cathode field emission display, thefirst panel is an anode panel in which an anode electrode and a phosphorlayer are formed, and the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed, or

(b) the flat-type display is a cold cathode field emission display, thefirst panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed.

In the present invention, the temperature range represented by the term“low-melting point” refers to a range including and below about 400° C.A general frit glass has a softening temperature of about 600° C., andthe firing temperature is 350° C. to about 500° C., so that the meltingpoint of the low-melting-point metal material constituting thelow-melting-point metal material layer or the low-melting-point metalmaterial for constituting the bonding layer for bonding the first paneland the second panel to each other in their circumferential portions isabout the same as, or lower than, the temperature employed for firingthe frit glass. There is no special limitation to be imposed on thelower limit of the melting point of the low-melting-point metalmaterial. However, when the above lower limit is too low, there may beposed a problem on the reliability of the low-melting-point metalmaterial layer and the bonding layer, so that the lower limit the abovemelting point is preferably 120° C. by taking account of the reliabilityof the flat-type display under general environments in which flat-typedisplays are used. That is, the melting point of the low-melting-pointmetal material for constituting the low-melting-point metal materiallayer or the bonding layer is 120° C. to 400° C., preferably 120° C. to300° C. In the present specification, the term “low-melting-point metalmaterial layer” includes a low-melting-point alloy material layer, andthe term “low-melting-point metal material” includes a low-melting-pointalloy material. The low-melting-point metal material constituting thelow-melting-point metal material layer and the low-melting-point metalmaterial constituting the bonding layer may be the samelow-melting-point metal material, may be low-melting-point metalmaterials of the same kinds, or may be low-melting-point metal materialsof different kinds. Further, the low-melting-point metal materialconstituting the low-melting-point metal material layer and thelow-melting-point metal material constituting the secondlow-melting-point metal material layer may be the same low-melting-pointmetal material, may be low-melting-point metal materials of the samekinds, or may be low-melting-point metal materials of different kinds.

The low-melting-point metal material includes In (indium; melting point157° C.); an indium-gold low-melting-point alloy; tin (Sn)-containinghigh-temperature solders such as Sn₈₀Ag₂₀ (melting point 220 to 370° C.)and Sn₉₅Cu₅ (melting point 227 to 370° C.); tin (Sn)-containing solderssuch as Sn₆₀Zn₄₀ (melting point 200 to 250° C.); lead (Pb)-containinghigh-temperature solders such as Pb_(97.5)Ag_(2.5) (melting point 304°C.), Pb_(94.5)Ag_(5.5) (melting point 304 to 365° C.) andPb_(97.5)Ag_(1.5)Sn_(1.0) (melting point 309° C.); zinc (Zn)-containinghigh-temperature solders such as Zn₉₅Al₅ (melting point 380° C.);tin-lead-containing standard solders such as Sn₅Pb₉₅ (melting point 300to 314° C.) and Sn₂Pb₉₈ (melting point 316 to 322° C.); and brazingmaterials such as Au₈₈Ga₁₂ (melting point 381° C.) (all of the aboveparenthesized values show atomic %). When the low-melting-point metalmaterial layer is heated to be melted, it is preferred to select alow-melting-point metal material such that the low-melting-point metalmaterial is melted at a temperature at which a substrate constitutingthe first panel such as a glass substrate is not damaged. Heating methodfor the low-melting-point metal material layer can be carried out byheating using a lump, a heater, a laser or a hot air furnace.

It is required to form the low-melting-point metal material layer on thetop surface of the spacer, in a portion where the spacer is to be fixedin the first panel effective field or in a portion where the spacer isto be fixed in the second panel effective field. In the followingexplanation, the top surface of the spacer, the portion where the spaceris to be fixed in the first panel effective field and the portion wherethe spacer is to be fixed in the second panel effective field will besometimes generally referred to as “bonding region” hereinafter. Thelow-melting-point metal material layer may be formed on the entiresurface of the bonding region, that is, in a continuous state on thebonding region, or may be formed in the form of spots (discontinuousform) on the bonding region. When it is formed in the form of spots(discontinuous form), it may be formed on at least one spot (forexample, a low-melting-point metal material layer having a diameter ofapproximately 30 μm is formed on only one spot along the entire lengthof the bonding) or it may be formed on a plurality of spots (forexample, low-melting-point metal material layers having a width of 60 μmand a length of 100 μm each are formed in the form of a broken line atintervals of approximately 0.5 mm).

The “forming” of the low-melting-point metal material layer refers to astate where the low-melting-point metal material layer is tightly bondedto the surface of the bonding region due to interatomic forces or astate where the low-melting-point metal material is diffused to form analloy layer in the bonding region. The forming of the abovelow-melting-point metal material layer can be accomplished, for example,by a vacuum thin film forming technique such as a vacuum vapordeposition method, a sputtering method, an ion plating method, or thelike, or can be accomplished by once melting the low-melting-point metalmaterial layer on the bonding region. The low-melting-point metalmaterial layer may be formed both on the top surface of the spacer andon the portion where the spacer is to be fixed in the first paneleffective field, or it may be formed both on the top surface of thespacer and on the portion where the spacer is to be fixed in the secondpanel effective field.

The “forming” of the low-melting-point metal material layer includes astate where the low-melting-point metal material layer is held on thesurface of the bonding region with gravitational force or frictionforce. This state will be referred to as “arrangement” of thelow-melting-point metal material layer for convenience. The arrangementof the low-melting-point metal material layer is accomplished by placingor attaching a wire or foil made of the low-melting-point metal materialon/to the surface of the bonding region. When the low-melting-pointmetal material layer can be held on the surface of the bonding regiondue to some adhesiveness that a foil has and when the bonding region hassome adhesiveness that prevents the low-melting-point metal materiallayer from coming off even when the holding surface is turned downward,the low-melting-point metal material layer can be also arranged both onthe top surface of the spacer and the portion where the spacer is to befixed in the first panel effective field or the second panel effectivefield. However, when the low-melting-point metal material layer such asa wire material that is simply held on the surface of the bonding regiondue to gravitational force is used, then preferably, thelow-melting-point metal material layer is arranged on one of thesurfaces of the spacer and the portion where the spacer is to be fixedin the first panel effective field or the second panel effective field.

When a natural oxidation film tends to grow on the surface of thelow-melting-point metal material layer, then suitably, the naturaloxidation film is removed from the low-melting-point metal materiallayer immediately before the low-melting-point metal material layer isheated. The natural oxidation film can be removed by a known method suchas a wet etching method using diluted hydrochloric acid, a dry etchingmethod using a chlorine-containing gas, an ultrasonic wave applicationmethod, or the like.

In the following explanation, the substrate for constituting the firstpanel or the substrate for constituting the second panel will bereferred to as “substrate for a panel”, and when the flat-type displayis a cold cathode field emission display, the substrate for constitutinga cathode panel will be sometimes referred to as “supporting member”,and the substrate for constituting an anode panel will be sometimesreferred to as “substratum”. Further, when there are employedexpressions that a constituent element for the first panel or the secondpanel is formed “on the substrate for panel”, that a constituent elementfor the cathode panel is formed “on the supporting member” and that aconstituent element is formed “on the substratum” hereinafter, theexpressions include both the formation of such a constituent elementdirectly on the substrate for panel, the supporting member or thesubstratum and the formation of such a component above the substrate forthe panel, the supporting member or the substratum.

Preferably, an electrically conductive layer is formed on thatportion/those portions of the first panel effective field and/or thesecond panel effective field which is/are in contact with the topsurface(s) of the spacer. When the flat-type display is a cold cathodefield emission display and when the top surface of the spacer comes incontact with the anode electrode formed in the anode panel, theformation of the above electrically conductive layer can be omitted.Preferably, the electrically conductive layer has excellent wettabilityto the low-melting-point metal material. The electrically conductivelayer can be constituted, for example, of a titanium (Ti) layer or anickel layer, or can be also constituted of a material for constitutinga gate electrode to be described later. When the flat-type display is acold cathode field emission display, for example, a stripe-shapedelectrically conductive layer extending in parallel with a stripe-shapedgate electrode is desirably formed on an insulating layer constitutingthe cathode panel, and the above electrically conductive layer ispreferably grounded for example. The formation of the above electricallyconductive layer can remove a voltage difference between the spacerconstituted of an insulating material and constituent elements of thefirst panel or the second panel, so that there can be suppressed theoccurrence of a discharge between the spacer and the constituentelements of the first panel or the second panel.

The spacer before fixed to the first panel effective field and/or thesecond panel effective field may have the form of a straight line alongits longitudinal direction or may be in the state of being curved alongits longitudinal direction. In these cases, there may be employed aconstitution in which a plurality of groups of spacer holders areprovided in the first panel effective field and/or the second paneleffective field, each group of spacer holders is constituted of aplurality of spacer holders, and the plurality of spacer holdersconstituting each group of spacer holders are positioned on a straightline. When the spacer in a state where it is fixed in the first paneleffective field and/or the second panel effective field is curved in itslongitudinal direction, and when the spacer is temporarily held in thespacer holders, a kind of counter force restoring the original shape ofthe spacer occurs in the spacer, and as a result, the spacer can bereliably held temporarily in the spacer holders.

When the spacer is curved along its longitudinal direction, it can be ina state where the form thereof is part of a circle, part of an ellipse,part of a parabola or part of any other curved line. The direction ofcurve of a certain portion of the spacer and the direction of a certainother portion thereof may be opposite. In other words, the spacer may becurved, for example, in the form of an “S” letter or may be curved inthe form of a plurality of “S” letters continued. Further, that aplurality of spacer holders constituting each group of spacer holdersare positioned on a straight line means that it is sufficient that theyshould be positioned on a straight line as the forming accuracy permits,and in a strict sense, they may not be positioned on a straight line.When the spacer is cut with an imaginary plane perpendicular to thelongitudinal direction thereof, the spacer has a cross-sectional form ofa long and narrow rectangle.

For reliably curving the spacer along its longitudinal direction,preferably, the surface roughness of one side surface of the spacer andthe surface roughness of the other side surface thereof are madedifferent. When the surface roughness of one side surface of the spacerand the surface roughness of the other side surface thereof are madedifferent, the amount of a strain generated on one side surface of thespacer and the amount of a strain generated on the other side surfacediffer from each other, so that the spacer can be reliably curved in itslongitudinal direction. Alternatively, for reliably curving the spaceralong its longitudinal direction, preferably, a strain-generating layeris formed on one side surface of the spacer. When the abovestrain-generating layer is formed on one side surface of the spacer, thespacer can be reliably curved along its longitudinal direction on thebasis of a strain generated in one side surface of the spacer due to thestrain-generating layer. Examples of the strain-generating layer includelayers constituted of Si₃N₄, SiO₂, SiC, SiCN, Al₂O₃, TiO₂, TiN, Cr₂O₃,Ta₂O₅, AlN and TaN.

In these cases, a so-called green sheet is formed, the green sheet isfired and the thus-obtained green sheet fired product is cut, wherebythe spacer can be produced. The green sheet fired product before orafter it is cut is polished, whereby the surface roughness of one sidesurface of the spacer and the surface roughness of the other sidesurface thereof can be made different from each other. Alternatively,the strain-generating layer can be formed on one surface of the greensheet fired product after or before it is cut. The method of forming thestrain-generating layer includes a physical vapor deposition method (PVDmethod), a chemical vapor deposition method (CVD method), platingmethods including an electric plating method and an electroless platingmethod, and a screen printing method. The physical vapor depositionmethod includes (1) vacuum deposition methods such as an electron beamheating method, a resistance heating method and a flash depositionmethod, (2) a plasma deposition method, (3) sputtering methods such as abipolar sputtering method, a DC sputtering method, a DC magnetronsputtering method, a high-frequency sputtering method, a magnetronsputtering method, an ion beam sputtering method and a bias sputteringmethod, and (4) ion plating methods such as a DC (direct current)method, an RF method, a multi-cathode method, an activating reactionmethod, an electric field deposition method, a high-frequency ionplating method and a reactive ion-plating method.

Alternatively, there may be also employed a constitution in which aplurality of groups of the spacer holders are formed in the first paneleffective field and/or the second panel effective field, each group ofthe spacer holders is constituted of a plurality of the spacer holders,and the plurality of the spacer holders constituting each group of thespacer holders are not positioned on a straight line. When a pluralityof the spacer holders constituting each group of the spacer holders arenot positioned on a straight line as described above, and when thespacer is temporarily held in the spacer holders, a kind of counterforce restoring the original shape of the spacer occurs in the spacer,and as a result, the spacer can be reliably held temporarily in thespacer holders. That a plurality of the spacer holders constituting eachgroup of the spacer holders are not positioned on a straight line meansthat an imaginary line connecting the plurality of the spacer holdersconstituting the group of the spacer holder is part of a circle, part ofan ellipse, part of a parabola, part of any other curved line excludinga straight line or a set of segments. The direction of curve of acertain portion of the imaginary line and the direction of curve ofother portions thereof may be opposite to each other. In other words,the imaginary line may be curved, for example, in the form of an “S”letter, or may be curved in the form of a plurality of “S” letters.Alternatively, the differential coefficient of the second order in acertain portion of the imaginary line may have a positive value, and thedifferential coefficient of the second order in other portion may have anegative value. That a plurality of the spacer holders constituting eachgroup of the spacer holders are not positioned on a straight line (thatis, positioned on an imaginary line) means that it is sufficient thatthey should be positioned on an imaginary line as the accuracy offorming the spacer holders permits, and they may not be strictlypositioned on the imaginary line. When the spacer is cut with animaginary plane at right angles with the longitudinal direction thereof,the spacer has a cross-sectional form of a long and narrow rectangle.The spacer before it is temporarily held on the spacer holders may havea constitution in which it has the form of a straight line along itslongitudinal direction, or may have a constitution in which it does nothave the form of a straight line (constitution in which the spacerbefore it is temporarily held on a group of the spacer holders has acurved state facing opposedly to the curved state of an imaginary lineconnecting a plurality of the spacer holders constituting the group ofthe spacer holders).

The spacer holders can be constituted, for example, from at least onemetal selected from the group consisting of nickel (Ni), cobalt (Co),iron (Fe), gold (Au), silver (Ag), rhodium (Rh), palladium (Pd),platinum (Pt) and zinc (Zn), or any one of alloys constituted of thesemetals; indium oxide-tin (ITO); indium oxide-zinc (IXO); tin oxide(SnO₂), antimony-doped tin oxide; indium- or antimony-doped titaniumoxide (TiO₂); ruthenium oxide (RuO₂), indium- or antimony-dopedzirconium oxide (ZrO₂); a polyimide resin; or a low-melting glass. Itcan be formed by a plating method including an electric plating methodand an electroless plating method, a thermal spraying method, a screenprinting method, a method using a dispenser, a sand blasting method, adry film method or a photo-sensitive method.

The above dry film method refers to a method in which a photosensitivefilm is laminated on a substrate for the panel, photosensitive film on aportion where the spacer holders are to be formed is removed by exposureand development, a material for forming the spacer holder is embedded inan opening generated by the removal, and the material for the spacerholders is fired. The photosensitive film is combusted and removed bythe firing, or removed with a chemical, and the material for forming thespacer holders, embedded in the opening, remains to constitute thespacer holders. The photo-sensitive method refers to a method in which aphotosensitive material layer for forming the spacer holders is formedon a substrate for the panel, the material layer is patterned byexposure and development and the material layer is fired. The sandblasting method refers to a method in which a material layer for formingthe spacer holders is formed on a substrate for the panel, for example,by screen printing or with a roll coater, a doctor blade, anozzle-ejection type coater, or the like, the material layer is driedand/or fired, then, a portion where the spacer holders are to be formedin the material layer for forming the spacer holders is covered with amask, and then, an exposed portion is removed by a sand blast method.

When the spacer holders are formed by a thermal spraying method, a maskmay be used so that no spacer holder is formed in an unnecessaryportion. The mask can be constituted from a so-called photosensitivematerial (e.g., photosensitive liquid resist material or aphotosensitive dry film). In this case, a photosensitive material layerformed of a photosensitive dry film is laminated on the substrate forthe panel. Alternatively, when the photosensitive material isconstituted from a photosensitive liquid resist material, aphotosensitive liquid resist-material layer is formed on the substratefor the panel. And, the photosensitive material layer is exposed anddeveloped, whereby a mask, which is formed of the photosensitive layerand has openings, can be formed on the substrate for the panel. Afterthe spacer holders are formed, the mask layer is removed from thesubstrate for the panel by a method that is selected as requireddepending upon the constitution of the mask. That is, for example, themask layer is chemically removed, (for example, peeled off with achemical or fired), or removed mechanically. Alternatively, the mask canbe constituted from a plate-shaped material (sheet-shaped material)prepared from a metal, glass, ceramics, a heat-resistant resin, or thelike. When the mask layer is constituted from a plate-shaped material(sheet-shaped material), openings can be made through such aplate-shaped material (sheet-shaped material) beforehand by machining,or the like, and the mask is placed on the substrate for the panel.After the spacer holders are formed, the mask is mechanically removed.

When the spacer holders are formed by a thermal spraying method, theycan be constituted from the following materials. That is, as a materialfor use in the thermal spraying method, it is preferred to use aheat-resistant material that is not altered, denatured or decomposed ata heat-treatment temperature in the step of producing the first panel orthe second panel (e.g., an anode electrode and a cathode electrode) orproducing the flat-type display (e.g., a cold cathode field emissiondisplay). Specific examples of the above material include ceramics, forexample, titanium oxides such as titania (TiO₂), chromium oxides such aschromia (Cr₂O₃), aluminum oxides such as alumina (Al₂O₃) and grayalumina (Al₂O₃.TiO₂), magnesium oxides such as magnesia (MgO) andmagnesia spinel (MgO.Al₂O₃), zirconium oxides such as zirconia (ZrO₂)and zircon (ZrO₂.SiO₂), silicon oxide, aluminum nitride, siliconnitride, zirconium nitride, magnesium nitride, tungsten carbide (WC),titanium carbide (TiC), silicon carbide (SiC) and chromium carbide(Cr₃C₂). Further, specific examples of the above material include metalmaterials such as aluminum (Al), copper (Cu), nickel (Ni), molybdenum(Mo), chromium (Cr), tungsten (W), titanium (Ti), rhenium (Re), vanadium(V) and niobium (Nb), and metal alloys such as nickel-chromium alloy,iron-nickel alloy, Kovar and ferrite. Further, glass can be used aswell, and there may be also used a mixture of at least two members ofceramics, metals, metal alloys and glasses. When the spacer holders areconstituted from an electrically conductive, thermally sprayablematerial, such a material can be selected from materials havingelectrical conductivity among the above-described various materials asrequired. For example, it is preferred to select such a material thatthe spacer holders have a volume resistivity of 1Ω·m or less. When thespacer holders are constituted from such a thermally sprayable material,the spacer holders and a partition wall to be described later work as akind of a wiring, so that, for example, the potential of an anodeelectrode can be reliably maintained at a predetermined value. Further,when a light-absorbing layer (which is also called black matrix) to bedescribed later is constituted from a thermally sprayable material thatabsorbs light from a phosphor layer, or when the spacer holders areconstituted from a thermal-sprayable material that absorbs light from aphosphor layer, it is sufficient to select such a thermally sprayablematerial among the above various materials as required, and it ispreferred to select, for example, a material that absorbs 99% or more oflight from a phosphor layer. The above material includes titanium oxide,chromium oxide and a mixture of titanium oxide and aluminum oxide. Insome cases, those portions of the spacer holders which are in contactwith the substrate for panel for constituting the first panel, or thesubstrate for panel for constituting the second panel, may beconstituted from an insulating thermally sprayable material, andportions above the above portions may be constituted from anelectrically conductive thermally sprayable material. The thermalspraying method or the thermal spraying method for forming thelight-absorbing layer from a thermally sprayable material that absorbslight, by a known thermal spraying method, include a plasma sprayingmethod, a flame spraying method, a laser spraying method and an arcspraying method.

When the spacer holders are formed by an electroless plating method, itis sufficient to use, as a catalyst, a water soluble salt or complex ofa chloride or nitrate of palladium, gold, silver, platinum, copper, andthe like.

For suppressing a thermal strain between the substrates for panelconstituting the first panel and second panel and the spacer holders,the spacer holders can be formed by a dispersion plating method using aplating solution prepared by dispersing an inorganic material such as ametal having a low thermal expansion coefficient or an organic materialhaving heat resistance. For example, when nickel is a parent phase,iron, SiO₂, SiN, polytetrafluoroethylene, or the like can be used as adispersion phase. The spacer holders may be coated with an electricallyconductive layer formed of a metal or an alloy. The electricallyconductive layer can be constituted from any material so long as it haselectrical conductivity. The method for forming the electricallyconductive layer includes various vacuum vapor deposition methodsincluding an electron beam vapor deposition method and a hot filamentvapor deposition method, a sputtering method, a CVD method, an ionplating method, a screen printing method, a plating method, and thelike.

For improving a thermal expansion coefficient deifference and adhesionbetween the spacer holders and the substrate for panel for constitutingthe first panel or the second panel (improving adhesion between thespacer holders and a light-absorbing layer when a light-absorbing layerto be described later is formed), or as a kind of cathode for platingwhen the spacer holders are formed by an electric plating method, anintermediate layer may be formed between them. The intermediate layerpreferably has a thermal expansion coefficient that is a value betweenthe thermal expansion coefficient of a material constituting the spacerholders and a material constituting the substrate for panel forconstituting the first panel or the second panel. Alternatively, theintermediate layer is preferably constituted from a material having agreater ductility than the substrate for the panel and having a smallerYoung's modulus than the substrate for the panel. For example, when thespacer holders are constituted of nickel, the material for constitutingthe intermediate layer can be selected from gold, silver or copper. Thethickness of the intermediate layer can be approximately 1 μm to 5 μm.The intermediate layer may have a layer-stacked structure.

In the present invention, after the spacer holders are formed, topsurfaces of the spacer holders may be polished to flatten the topsurfaces of the spacer holders.

In the present invention, when the flat-type display is a cold cathodefield emission display, a plurality of cold cathode field emissiondevices are formed in a cathode panel, and a phosphor layer and an anodeelectrode are formed in an anode panel. The anode panel is preferablyprovided with a plurality of separation walls for preventing theoccurrence of a so-called optical crosstalk (color mixing) that iscaused when electrons recoiling from the phosphor layer or secondaryelectrons emitted from the phosphor layer enter another phosphor layer,or for preventing the collision of electrons with another phosphor layerwhen electrons recoiling from the phosphor layer or secondary electronsemitted from the phosphor layer enter another phosphor layer over theseparation wall.

As will be described in detail with regard to some of them, examples ofthe cold cathode field emission device (to be abbreviated as “fieldemission device” hereinafter) include

(a) a Spindt type field emission device (field emission device in whicha conical electron emitting portion is formed on a cathode electrodepositioned in a bottom of a hole portion),

(b) a crown type field emission device (field emission device in which acrown-shaped electron emitting portion is formed on a cathode electrodepositioned in a bottom of a hole portion),

(c) a plane type field emission device (field emission device in which anearly plane-surface-shaped electron emitting portion is formed on acathode electrode positioned in a bottom of a hole portion),

(d) a flat type field emission device that emits electrons from thesurface of a flat cathode electrode,

(e) a crater type field emission device that emits electrons from convexportions of surface of a cathode electrode having a convexoconcave shapeformed on the surface, and

(f) an edge type field emission device that emits electrons from an edgeportion of a cathode electrode.

In the anode panel, the portion with which electrons emitted from thefield emission device collide first is an anode electrode or a phosphorlayer although it is dependent upon the structure of the anode panel.

The surface form (pattern) of the phosphor layer may be the form of dotsor may be the form of a stripe depending upon pixels. When the phosphorlayer is formed between partition walls, the phosphor layer is formed onthat portion of the substratum constituting the anode panel which issurrounded with the partition walls.

The phosphor layer can be formed from a luminescence crystal particlecomposition prepared from luminescence crystal particles (e.g., phosphorparticles having a particle diameter of approximately 5 to 10 nm), forexample, by a method in which a red photosensitive luminescence crystalparticle composition (red phosphor slurry) is applied to the entiresurface, followed by exposure and development, to form a phosphor layerthat emits light in red, then, a green photosensitive luminescencecrystal particle composition (green phosphor slurry) is applied to theentire surface, followed by exposure and development, to form a phosphorlayer that emits light in green, and further a blue photosensitiveluminescence crystal particle composition (blue phosphor slurry) isapplied to the entire surface, followed by exposure and development, toform a phosphor layer that emits light in blue, although it shall not belimited thereto.

The phosphor material for constituting the luminescence crystalparticles can be selected from conventionally known phosphor materialsas required. In the case of displaying in color, it is preferred tocombine phosphor materials whose color purities are close to threeprimary colors defined in NTSC, which attains a white balance when threeprimary colors are mixed, whose afterglow time period is small and whichattains nearly equal afterglow time periods of the three primary colors.Examples of the phosphor material for constituting the phosphor layerthat emits light in red include (Y₂O₃:Eu), (Y₂O₂S:Eu), (Y₃Al₅O₁₂:Eu),(YBO₃:Eu), (YVO₄:Eu), (Y₂SiO₅:Eu),(Y_(0.96)P_(0.60)V_(0.40)O₄:Eu_(0.04)), [(Y, Gd)BO₃:Eu], (GdBO₃:Eu),(ScBO₃:Eu), (3.5MgO.0.5MgF₂.GeO₂:Mn), (Zn₃(PO₄)₂:Mn), (LuBO₃:Eu) and(SnO₂:Eu). Examples of the phosphor material for constituting thephosphor layer that emits light in green include (ZnSiO₂:Mn),(BaAl₁₂O₁₉:Mn), (BaMg₂Al₁₆O₂₇:Mn), (MgGa₂O₄:Mn), (YBO₃:Tb), (LuBO₃:Tb),(Sr₄Si₃O₈Cl₄:Eu), (ZnS:Cu,Al), (ZnS:Cu,Au,Al), (ZnBaO₄:Mn), (GbBO₃:Tb),(Sr₆SiO₃Cl₃:Eu), (BaMgAl₁₄O₂₃:Mn), (ScBO₃:Tb), (Zn₂SiO₄:Mn), (ZnO:Zn),(Gd₂O₂S:Tb) and (ZnGa₂O₄:Mn). Examples of the phosphor material forconstituting the phosphor layer that emits light in blue include(Y₂SiO₅:Ce), (CaWO₄:Pb), CaWO₄, YP_(0.85)V_(0.15)O₄, (BaMgAl₁₄O₂₃:Eu),(Sr₂P₂O₇: Eu), (Sr₂P₂O₇:Sn), (ZnS:Ag,Al), (ZnS:Ag), ZnMgO and ZnGaO₄.

The material for constituting the anode electrode can be selecteddepending upon the constitution of the cold cathode field emissiondisplay. That is, when the cold cathode field emission display is atransmission type (the anode panel corresponds to a display screen), andwhen the anode electrode and the phosphor layer are stacked on thesubstrate in this order, not only the substrate on which the anodeelectrode is to be formed but also the anode electrode itself isrequired to be transparent, and a transparent electrically conductivematerial such as indium-tin oxide (ITO) is used. When the cold cathodefield emission display is a reflection type (the cathode panelcorresponds to a display screen), or when the cold cathode fieldemission display is a transmission type and the phosphor layer and theanode electrode are stacked on the substrate in this order, ITO can beused, and besides ITO, aluminum (Al) or chromium (Cr) is used forconstituting the anode electrode. When the anode electrode is made ofaluminum (Al) or chromium (Cr), for example, the specific thickness ofthe anode electrode is 3×10⁻⁸ m (30 nm) to 1.5×10⁻⁷ m (150 nm),preferably 5×10⁻⁸ m (50 nm) to 1×10⁻⁷ m (100 nm). The anode electrodecan be formed by a vacuum vapor deposition method or a sputteringmethod.

Examples of the constitution of the anode electrode and the phosphorlayer include

(1) a constitution in which the anode electrode is formed on thesubstratum and the phosphor layer is formed on the anode electrode, and

(2) a constitution in which the phosphor layer is formed on thesubstratum and the anode electrode is formed on the phosphor layer.

In the above constitution (1), a so-called metal back film which is incontact with the anode electrode may be formed on the phosphor layer,and in the above constitution (2), a metal back film may be formed onthe anode electrode. Preferably, the partition wall is formed on thesubstratum. In the case of (1), the spacer holders or the partition wallare/is sometimes formed on the anode electrode. This case is alsoincluded in the concept that the spacer holders or the partition wallare/is formed on the substratum.

When a plurality of the partition walls are provided, there can beemployed a constitution in which part of the plurality of the partitionwalls work as spacer holders, and in this case, the partition walls canbe formed simultaneously (together) with the spacer holders. The spacerholders and the partition wall(s) can be also formed separately, and inthis case, the plane form of the spacer holders can include the form ofa circle as an example.

The plane form of the partition wall can include the form of a lattice(grid), that is, a form that surrounds a phosphor layer corresponding toone pixel and having a plane form of a nearly rectangle (in the form ofa dot). The plane form of the partition wall can also include aband-shaped or stripe-shaped form that extends in parallel with twoopposite sides of a nearly rectangular or stripe-shaped phosphor layer.When the partition wall has the form of a lattice, the form may be thatwhich continuously encompasses the four sides of one phosphor layerregion or that which discontinuously encompasses the four sides of onephosphor layer region. When the partition wall has a band-shaped form ora stripe-shaped form, the form may be a continuous form or may be adiscontinuous form. After the partition wall is formed, the partitionwall may be polished to flatten the top surface of the partition wall.The partition wall can be formed, for example, by the same method as theabove-explained method of forming the spacer holders.

In the method for manufacturing a flat-type display, provided by thepresent invention including various aspects, when the flat-type displayis a cold cathode field emission display, it is preferred from theviewpoint of an improvement in contrast of display images to include thestep of a light-absorbing layer, which absorbs light from the phosphorlayer, on the substratum in a region between phosphor layer and phosphorlayer constituting the anode panel (in this region, for example, thespacer holders or the partition wall are/is formed). The abovelight-absorbing layer works as a so-called black matrix. As a materialfor constituting the light-absorbing layer, it is preferred to select amaterial that absorbs 99% or more of light from the phosphor layer. Theabove material includes carbon, a metal thin film (such as chromium,nickel, aluminum, molybdenum, etc., or alloys of these), and metaloxides (such as chromium oxide), metal nitrides (such as chromiumnitride), a heat-resistant organic resin, glass paste and a glass pastecontaining electrically conductive particles of a black pigment, silver,or the like. Specific examples thereof include a photosensitivepolyimide resin, chromium oxide and a chromium oxide/chromium stackedfilm. In the chromium oxide/chromium stacked film, the chromium film isin contact with the substratum. The light-absorbing layer can be formed,for example, by a combination of a vacuum vapor deposition method or asputtering method with an etching method, a combination of a vacuumvapor deposition method, a sputtering method or a spin coating methodwith a lift-off method, a screen printing method, or a lithographytechnique, which are properly selected depending upon a material used.In the above case (1) and when the spacer holder or the partition wallare/is formed on the anode electrode, the light-absorbing layer may beformed between the substratum and the anode electrode, or it may beformed between the anode electrode and the spacer holders.

When the first panel and the second panel are bonded to each other intheir circumferential portions, they may be bonded to each other using abonding layer, or they may be bonded to each other using a combinationof a frame formed of an insulating rigid material such as glass,ceramics, or the like with a bonding layer. When the frame and thebonding layer are used in combination, the facing distance of the firstpanel and the second panel can be increased so that the distance islonger than that attained when the bonding layer alone is used. As amaterial for constituting the bonding layer, a frit glass may be used ora low-melting-point metal material having a melting point ofapproximately 120 to 400° C. may be used as already described. Differingfrom a frit glass used in the state of a high-viscosity paste, thelow-melting-point metal material does not trap gas foams in a layer whenconstituted as a bonding layer, and it is also excellent in dimensionalaccuracy with regard to the width and thickness of the bonding layer.When the bonding layer formed of the low-melting-point metal material isused, therefore, there can be prevented the vacuum-degree deteriorationthat is caused on the flat-type display with the passage of time bydegassing or a bonding failure, and the flat-type display can beremarkably improved in performance and long-term reliability.

When the bonding layer is constituted from the low-melting-point metalmaterial layer, it is required to form or arrange the bonding layer in asubstrate for constituting the first panel (to be referred to as“substrate for the first panel”), a substrate for constituting thesecond panel (to be referred to as “substrate for the second panel”) orthe frame in advance. The above “forming” of the bonding layer refers toa state where the bonding layer adheres tightly to the surface of thesubstrate for the first panel, the substrate for the second panel or theframe due to interatomic forces. The above forming of the bonding layercan be accomplished, for example, by a vacuum thin film formingtechnique such as a vacuum vapor deposition method, a sputtering method,an ion plating method, or the like, or by once melting the bonding layeron the surface of the substrate for the first panel, the substrate forthe second panel or the frame. Alternatively, the “arranging” of thebonding layer refers to a state where the bonding layer is held on thesurface of the substrate for the first panel, the substrate for thesecond panel or the frame due to gravitational force or frictionalforce. The “arranging” of the bonding layer can be accomplished byplacing or attaching a wire material or foil formed of thelow-melting-point metal material on/to the surface of the substrate forthe first panel, the substrate for the second panel or the frame. Whenthere is used a bonding layer that can be held on the surface of thesubstrate for the first panel, the substrate for the second panel or theframe, since it has adhesiveness like a foil and that does not come offeven if the holding surface is turned downward in some cases, then thebonding layers can be also arranged both on the substrate for the firstpanel and the substrate for the second panel, both on the substrate forthe first panel and the frame, or both on the substrate for the secondpanel and the frame. However, when there is used a bonding layer that isheld on the surface of the substrate for the first panel, the substratefor the second panel or the frame like a wire material, then preferably,the bonding layer is arranged on one of the substrate for the firstpanel and the substrate for the second panel, on one of the substratefor the first panel and the frame, or on one of the substrate for thesecond panel and the frame.

When the three members such as the first panel, the second panel and theframe are bonded, these three members may be bonded at the same time, orone of the first panel and the second panel and the frame may be bondedto each other in a first stage, and the other of the first panel and thesecond panel and the frame may be bonded to each other in a secondstage. As a material for constituting the bonding layer for use in thefirst stage and a material for constituting the bonding layer in thesecond stage, the same material may be used, materials of the same kindsmay be used, or materials of different kinds may be used. That is, theremay be employed a constitution in which the bonding layer for use in thefirst stage (to be referred to as “first bonding layer”) is formed of alow-melting-point metal material, and the melting point of thelow-melting-point metal material for constituting the first bondinglayer and the melting point of the low-melting-point metal material forconstituting the bonding layer for use in the second stage (to bereferred to as “second bonding layer”) are about the same (for example,these melting points are different by approximately 0° C. to 100° C.).When the above constitution is employed, bonding of the first panel andthe frame and bonding of the second panel and the frame can be carriedout simultaneously, so that a residual thermal strain in the flat-typedisplay produced can be decreased. Alternatively, there may be alsoemployed a constitution in which the first bonding layer is formed of alow-melting-point metal material, and the melting point of thelow-melting-point metal material for constituting the first bondinglayer is higher than the melting point of a low-melting-point metalmaterial for constituting the second bonding layer. When the aboveconstitution is employed, bonding of the first panel and the frame andbonding of the second panel and the frame can be carried out inindependent heating processes, so that a flat-type display produced canbe improved in assembly accuracy. Further, there may be employed aconstitution in which the first bonding layer is formed from a fritglass (also called “glass paste”). The frit glass has a high insulationproperty that the low-melting-point metal material cannot be expected tohave. Therefore, when the flat-type display is, for example, inaccordance with a high-voltage specification and when a thin insulatingfilm such as a passivation film or the like formed on the first panel orthe second panel is hence not sufficient for an adequate insulationproperty, the constitution using a frit glass is remarkably effective.Alternatively, there may be also employed a constitution in which partof the first bonding layer is formed from a frit glass, and theremaining portion of the first bonding layer is formed of alow-melting-point metal material. In the first bonding layer, theportion formed of a frit glass and the remaining portion formed of alow-melting-point metal material may have any arrangement in a regionwhere the first bonding layer is to be formed. For example, a pluralityof “part”s may scattered in the remaining portion.

For example, when the first panel includes an electrode that is led outof the flat-type display, there can be employed a constitution in whichonly the circumferential portion of the electrode is coated with a fritglass. Further, when the first panel or the second panel includes anelectrode that is led out of the flat-type display, an insulating filmcan be formed on the electrode, and the first bonding layer and thesecond bonding layer can be formed or arranged on the insulating film.In the above constitution, the first panel or the second panel includesthe above insulating film. Alternatively, an insulating film (e.g., anoxide film of a material constituting the electrode) may be formed onthat portion (surface) of the electrode which is in contact with thefirst bonding layer or the second bonding layer.

When bonding of the three members or bonding at the second stage iscarried out in a high-vacuum atmosphere, a space surrounded by the firstpanel, the second panel, the frame and the adhesive layer comes to be avacuum space upon bonding. Otherwise, after the three members arebonded, the space surrounded by the first panel, the second panel, theframe and the adhesive layer may be vacuumed to obtain a vacuum space.When the vacuuming is carried out after the bonding, the pressure in anatmosphere during the bonding may be any one of atmospheric pressure andreduced pressure, and the gas constituting the atmosphere may be ambientatmosphere or an inert gas containing nitrogen gas or a gas (forexample, Ar gas) coming under the group 0 of the periodic table.

The bonding is usually carried out by heating, and the heating can becarried out by a known heating method such as heating using a lump, aheater, a laser or a hot air furnace.

When the bonding is followed by discharging of a gas, the dischargingcan be carried out through a chip tube pre-connected to the first paneland/or the second panel. The chip tube is, typically, constituted from aglass tube, it is bonded to a circumferential portion of a perforatedportion provided in the ineffective field of the first panel and/or thesecond panel with a frit glass or the above low-melting-point metalmaterial, and after the space reaches a predetermined vacuum degree, itis sealed off by heat fusion. Before the above sealing off, preferably,the entire flat-type display is once heated and temperature-decreased,since a residual gas can be released into the space and the residual gascan be discharged out of the space. When a cold cathode field emissiondisplay is intended as a flat-type display, the vacuum degree requiredis in the order of approximately 10⁻² Pa or higher (that is, a lowerpressure).

When the three members, the first panel, the second panel and the frame,are bonded, or when the first panel and the second panel are bondedwithout the frame, the low-melting-point metal material layer fixing thespacer in the first panel effective field may be re-melted. However, thespacer is already arranged between the first panel effective field andthe second panel effective field which work as a display portion, andthe spacer is no longer in any freely movable state, so that there iscaused no substantial problem.

When the bonding layer is constituted from a low-melting-point metalmaterial, then desirably, the low-melting-point metal material isexcellent in wettability to the substrate for the first panel, thesubstrate for the second panel or the frame. When the above condition ofwettability is not satisfied, then preferably, a wettability-improvinglayer is formed on the substrate for the first panel, the substrate forthe second panel or the frame. When the low-melting-point metal materialhas poor wettability to the surface of the substrate for the firstpanel, the surface of the substrate for the second panel or the surfaceof the frame, the above wettability-improving layer may be formed. As aresult, the low-melting-point metal material is constricting on thewettability-improving layer in a self-aligning manner upon completion ofthe final bonding after heating due to the surface tension of thelow-melting-point metal material, so that even if the accuracy ofpositioning the wettability-improving layer and the bonding layer is notso high before the heating, there can nevertheless be obtained the meritof the wettability-improving layer and the bonding layer being finallypositioned accurately. As a material for constituting thewettability-improving layer, examples of the material include titanium(Ti), nickel (Ni) and copper oxide (CuO). It is sufficient that thewettability-improving layer should have a thickness of about 0.1 μm.When a natural oxide film tends to grow on the surface of thewettability-improving layer, then suitably, the natural oxide film isremoved from the surface of the wettability-improving layer immediatelybefore the bonding layer, the first bonding layer or the second bondinglayer is formed. The natural oxide film can be removed by a known methodsuch as an etching method, an ultrasonic wave application method, or thelike. As a method for forming the wettability-improving layer, examplesof the method include vacuum thin film forming techniques such as avacuum vapor method, a sputtering method, an ion plating method, etc.,and a plating method.

When the bonding layer is constituted from a low-melting-point metalmaterial, and when a natural oxide film tends to grow on the surface ofthe bonding layer, the first bonding layer or the second bonding layer,it is preferable to remove the natural oxide film from the bonding layersurface immediately before the heating-applied bonding. The naturaloxide film can be removed by a known method such as a wet etching methodusing diluted hydrochloric acid, a dry etching method using achlorine-containing gas, an ultrasonic wave application method, or thelike.

Each of the substrate for the first panel, the substrate for the secondpanel, the substrate (supporting member) for constituting the cathodepanel and the substrate (substratum) for constituting the anode panelcan be any substrate so long as the surface thereof is constituted atleast from an insulating member, and they include a glass substrate, aglass substrate having an insulating film formed on its surface, aquartz substrate, a quartz substrate having an insulating film formed onits surface and a semiconductor substrate having an insulating filmformed on its surface. From the viewpoint of decreasing a productioncost, it is preferred to use a glass substrate or a glass substratehaving an insulating film formed on its surface.

In the present invention, since the spacer is fixed to the first paneleffective field and/or the second panel effective field with thelow-melting-point metal material layer, the tilting or falling of thespacer in the process of producing a flat-type display can be reliablyprevented, and the present invention is free from the problems wherein agas is released from a material fixing the spacer in variousheat-treatment steps in the process of producing a flat-type display andwherein the material fixing the spacer is thermally deteriorated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic partial end view of a cold cathode field emissiondisplay that is a flat-type display in Example 1.

FIG. 2 is an enlarged schematic end view of part of the cold cathodefield emission display that is the flat-type display in Example 1.

FIG. 3 is a schematic layout drawing of layout of a partition wall,spacer holders, a spacer and a phosphor layer in an anode panelconstituting the cold cathode field emission display that is theflat-type display in Example 1.

FIG. 4 is a schematic layout drawing of variant of the layout of apartition wall, spacer holders, a spacer and a phosphor layer in ananode panel constituting the cold cathode field emission display that isthe flat-type display in Example 1.

FIG. 5 is a schematic layout drawing of another variant of the layout ofa partition wall, spacer holders, a spacer and a phosphor layer in ananode panel constituting the cold cathode field emission display that isthe flat-type display in Example 1.

FIG. 6 is a partial perspective view of a cathode panel constituting thecold cathode field emission display that is the flat-type display inExample 1.

FIGS. 7(A) to 7(D) are schematic partial end views of a substratum,etc., for explaining the method for producing an anode panel in Example1.

Following FIG. 7(D), FIGS. 8(A) to 8(C) are schematic partial end viewsof the substratum, etc., for explaining the method for producing theanode panel in Example 1.

FIG. 9 is a schematic partial end view of a variant of a cold cathodefield emission display that is a flat-type display in Example 2.

FIG. 10 is an enlarged schematic end view of part of the cold cathodefield emission display that is the flat-type display in Example 2.

FIGS. 11(A), 11(B) and 11(C) are a schematic drawing obtained by viewinga spacer from the side of a top surface, a schematic drawing of layoutof spacer holders, and a drawing schematically showing a state where thespacer is held with the spacer holders in Example 7.

FIG. 12(A) and 12(B) are a drawing schematically showing a layout ofspacer holders and a drawing schematically showing a state where aspacer is held with the spacer holders in a variant of Example 7.

FIGS. 13(A) and 13(B) are schematic partial end views of a supportingmember, etc., for explaining a method for manufacturing a Spindt typecold cathode field emission device.

Following FIG. 13(B), FIGS. 14(A) and 14(B) are schematic partial endviews of the supporting member, etc., for explaining the method formanufacturing the Spindt type cold cathode field emission device.

FIGS. 15(A) and 15(B) are schematic partial end views of a supportingmember, etc., for explaining a method for manufacturing a plane typecold cathode field emission device (No. 1).

Following FIG. 15(B), FIGS. 16(A) and 16(B) are schematic partial endviews of the supporting member, etc., for explaining the method formanufacturing the plane type cold cathode field emission device (No. 1).

FIGS. 17(A) and 17(B) are a schematic partial cross-sectional view of aplane type cold cathode field emission device (No. 2) and a schematicpartial cross-sectional view of a flat type cold cathode field emissiondevice.

FIG. 18 is a schematic partial end view of a Spindt type cold cathodefield emission device having a focus electrode.

FIG. 19 is a schematic partial end view of another variant of the coldcathode field emission display that is the flat-type display in Example3.

FIG. 20 is a schematic partial end view of still another variant of thecold cathode field emission display that is the flat-type display inExample 3.

FIGS. 21(A) to (D) are schematic partial plan views showing variants oflayout of spacer holders.

FIG. 22 is a schematic partial end view of a cold cathode field emissiondisplay that is a conventional flat-type display.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be explained on the basis of Examples andwith reference to the drawings.

EXAMPLE 1

Example 1 is directed to the flat-type display of the present invention,and more specifically, to the flat-type display according to the first-Caspect (“case 22” in Table 1). Further, it is directed to the method formanufacturing a flat-type display, provided according to the firstaspect of the present invention, and more specifically, to the methodfor manufacturing a flat-type display, provided according to each of thefirst-A and first-B aspects of the present invention (“case 42” in Table2). In Example 1, the flat-type display is a cold cathode field emissiondisplay (to be simply abbreviated as “display” hereinafter).

FIG. 1 shows a schematic partial end view of the display (so-calledthree-electrode type display) of Example 1, FIG. 2 shows an enlargedschematic end view of part of the display, FIGS. 3 to 5 show layoutdrawings schematically showing layouts of partition walls 22 andphosphor layers 23 in an anode panel AP constituting the display, andFIG. 6 shows a schematic partial perspective view of a cathode panel CP.FIG. 1 corresponds to an end view, for example, which is taken alongline A-A in FIG. 3.

In the display of Example 1, the first panel (anode panel AP) and thesecond panel (cathode panel CP) are bonded to each other in theircircumferential portions, and a space interposed between the first panel(anode panel AP) and the second panel (cathode panel CP) is in a vacuumstate. In the anode panel AP, an anode electrode and a phosphor layerare formed, and in the cathode panel CP, a plurality of cold cathodefield emission devices (to be abbreviated as “field emission devices”hereinafter) are formed.

The anode panel AP is constituted, for example, of a substratum 20formed of a glass substrate, a phosphor layer 23 (in a color display, aphosphor layer 23R that emits light in red, a phosphor layer 23G thatemits light in green and a phosphor layer 23B that emits light in blue)that is formed on the substratum 20 and has a predetermined pattern, andan anode electrode 24 that is formed thereon, works as a reflection filmand is formed of an aluminum thin film. Partition walls 22 are formed onthe substratum 20, and the phosphor layer 23 is formed on that portionof the substratum which is between partition wall 22 and partition wall22. The anode electrode 24 is formed on the entire first panel effectivefield while ranging from a portion on the phosphor layer 23 to portionson the partition walls 22. In the anode panel AP shown in FIG. 1, alight-absorbing layer (black matrix) 21 for absorbing light from thephosphor layer 23 is formed between the partition wall 22 and thesubstratum 20. The light-absorbing layer 21 is formed of a chromiumoxide/chromium stacked film.

A field emission device formed in the cathode panel CP of the displayshown in FIG. 1 is a so-called Spindt type field emission device havinga conical electron emitting portion 15. The field emission device isconstituted of a cathode electrode 11 formed on a supporting member 10,an insulating layer 12 formed on the supporting member 10 and thecathode electrode 11, a gate electrode 13 formed on the insulating layer12, an opening portion 14 made through the gate electrode 13 and theinsulating layer 12 (a first opening portion 14A made through the gateelectrode 13 and a second opening portion 14B made through theinsulating layer 12), and a conical electron emitting portion 15 formedon the cathode electrode 11 positioned in the bottom of the openingportion 14. Generally, the cathode electrode 11 and the gate electrode13 are formed in the form of stripes in the directions in whichprojection images of these two electrodes cross each other at rightangles, and generally, a plurality of field emission devices are formedin a region corresponding to a portion where the projection images ofthese two electrodes overlap (the region corresponding to a regionoccupying one pixel and being an electron emitting region EA). Further,such electron emitting regions EA are generally arranged in atwo-dimensional matrix in the effective field of the cathode panel CP.

Each pixel is constituted of the electron emitting region EA on thecathode panel side and the phosphor layer 23 that faces the electronemitting region EA and is on the anode panel side. In the effectivefield, such pixels are arranged in the order of hundreds of thousands toseveral millions.

A spacer 31 formed of alumina (Al₂O₃) is disposed between the firstpanel effective field and the second panel effective field which work asa display portion, and the spacer 31 is fixed to the first paneleffective field and the second panel effective field with alow-melting-point metal material layer 33A and a low-melting-point metalmaterial layer 33B formed of Sn₆₀-Zn₄₀ (melting point 200 to 250° C.).More specifically, one surface 31A of the spacer 31 is fixed onto theanode electrode 24 with the low-melting-point metal material layer 33A.The other surface 31B of the spacer 31 is fixed onto the electricallyconductive layer 16 having the form of a stripe with a low-melting-pointmetal material layer 33B. The above electrically conductive layer 16having the form of a stripe is formed on the insulating layer 12 andextends in parallel with the gate electrode 13 having the form of astripe. Conductive material layers 32A and 32B made of titanium areformed so as to coat both the surfaces 31A and 31B of the spacer 31.FIG. 6 omits showing of the electrically conductive layer 16.

When the spacer 31 is cut with an imaginary plane at right angles withits longitudinal direction, the spacer 31 has a cross-sectional form ofa long and narrow rectangle. Further, the spacer 31 has the form of astraight line along its longitudinal direction before it is fixed to thefirst panel effective field and the second panel effective field. Thespacer 31 has a length of approximately 100 mm, a thickness ofapproximately 50 μm and a height of approximately 1 mm.

The spacer 31 can be produced by forming a so-called green sheet, firingthe green sheet and cutting the thus-obtained green sheet fired product.Conductive material layers 32A and 32B made of Ti are formed so as tocover both surfaces 31A and 31B of the spacer 31, for example, by asputtering method, and further, low-melting-point metal material layers33A and 33B are formed on the conductive material layers 32A and 32B bya vacuum vapor deposition method.

A plurality of spacer holders for temporarily holding the spacer areformed in the first panel effective field that works as a displayportion, and each group of the spacer holders is constituted of aplurality of spacer holders 30. That is, the plurality of the spacerholders 30 are provided to the anode panel AP that is the first panel.The plurality of spacer holders 30 constituting each group of the spacerholders are positioned on a nearly straight line. The spacer 31 isarranged (temporarily held) between the first panel effective field andthe second panel effective field which work as a display portion with aplurality of the spacer holders 30 constituting the groups of the spacerholders. Specifically, the bottom portion of the spacer 31 is insertedbetween spacer holder 30 and spacer holder 30.

End portions of some of partition walls 22 have the form of letter “T”,and a horizontal bar portion of the letter “T” corresponds to a spacerholder 30. The spacer holders 30 were formed at intervals of 1 mm.Further, each pair of the spacer holders 30 had a distance of 55 μmbetween them and a height of approximately 50 μm. Projection portionsmay be formed on end portions of some of the partition walls 22, and thespacer holders may be constituted of the projection portions. Further,separately from the partition walls 22, for example, bump-shaped spacerholders 30 may be formed, and this is also applicable to Examples to bedescribed hereinafter.

FIGS. 3 to 5 schematically show arrangement states of the partitionwalls 22, the spacer holders 30, the spacer 31 and the phosphor layer 23(23R, 23G, 23B). In FIGS. 3 to 5, the partition walls 22, the spacerholders 30 and the spacer 31 are provided with slanting lines forclearly showing them. In an example shown in FIG. 3 or FIG. 4, eachpartition wall 22 has the plane form of a lattice (grid). That is, ithas a form in which it surrounds the phosphor layer 23 corresponding toone pixel and having a plane form, for example, of a substantialrectangle (dot form). On the other hand, in an example shown in FIG. 5,the partition wall 22 has the plane form of a band or stripe extendingalong two opposed sides of a substantially rectangular phosphor layer23. In the example shown in FIG. 5, the partition wall 22 has a lengthof approximately 200 μm, a width (thickness) of approximately 25 μm anda height of approximately 50 μm. Further, the gap between partition wall22 and partition wall 22 along the length direction thereof isapproximately 100 μm, and the forming pitch of the partition walls 22along the width (thickness) direction is approximately 110 μm. Thehorizontal bar portion of the letter “T” portion of the partition wallconstituting the spacer holder 30 has a length of approximately 40 μm.

A relatively negative voltage is applied to the cathode electrode 11from a cathode-electrode control circuit 40, a relatively positivevoltage is applied to the gate electrode 13 from a gate-electrodecontrol circuit 41, and a voltage far higher than the voltage to beapplied to the gate electrode 13 is applied to the anode electrode 24from an anode-electrode control circuit 42. When this display is usedfor display, for example, scanning signals are inputted to the cathodeelectrode 11 from the cathode-electrode control circuit 40, and videosignals are inputted to the gate electrode 13 from the gate-electrodecontrol circuit 41. Reversely thereto, video signals may be inputted tothe cathode electrode 11 from the cathode-electrode control circuit 40,and scanning signals may be inputted to the gate electrode 13 from thegate-electrode control circuit 41. Due to an electric field generatedwhen a voltage is applied between the cathode electrode 11 and the gateelectrode 13, electrons are emitted from the electron emitting portion15 on the basis of the quantum tunnel effect, and the electrons aredrawn toward the anode electrode 24, pass the anode electrode 24 andcollide with the phosphor layer 23. That is, the operation andbrightness of this display are basically controlled by the voltageapplied to the gate electrode 13 and the voltage applied to the electronemitting portion 15 through the cathode electrode 11.

One surface 31A of the spacer 31 is electrically connected to the anodeelectrode 24 through a conductive material layer 32A and alow-melting-point metal material layer 33A, so that a discharge betweenthe one surface 31A of the spacer 31 and the anode electrode 24 can beprevented. On the other hand, the other surface 31B of the spacer 31 iselectrically connected to an electrically conductive layer 16 through alow-melting-point metal material layer 33B and a conductive materiallayer 32B, so that a discharge between the other surface 31B of thespacer 31 and the electrically conductive layer 16 can be prevented. Theelectrically conductive layer 16 is grounded.

The method for manufacturing the display of Example 1 shown in FIGS. 1and 3 will be explained below with reference to FIGS. 7(A) to 7(D) andFIGS. 8(A) to 8(C) showing schematic partial end views of a substratumconstituting the anode panel AP or the substratum 20, and the like.

[Step-100]

First, the partition walls 22 and the spacer holders 30 are formed onthe substratum 20 made of a glass substrate. Specifically, first, aresist layer is formed on the entire surface of the substratum 20,followed by exposure and development, to remove the resist layer onportions where the partition walls 22 and the spacer holders 30 are tobe formed in the substratum 20. Then, a chromium film and a chromiumoxide film are consecutively formed on the entire surface by a vacuumvapor deposition method, and then the resist layer and the chromium filmand chromium oxide film on the resist layer are removed, In this manner,a light-absorbing layer 21 that works as a black matrix can be formed onthe portion where the partition wall 22 and the spacer holders 30 are tobe formed in the substratum 20 (see FIG. 7(A)).

[Step-110]

Then, an alkali-soluble photosensitive dry film having a thickness of 50μm is stacked on the entire surface, specifically, on the substratum 20and the light-absorbing layer 21, followed by exposure and development,to arrange a mask (photosensitive dry film 34) having an opening 35 onthe substratum 20, so that portions (the light-absorbing layer 21) wherethe partition walls 22 and the spacer holders 30 are to be formed in thesubstratum 20 can be exposed (see FIG. 7(B)).

[Step-120]

Then, a thermally sprayable material made of chromium (Cr) (which is anelectrically conductive thermally sprayable material) is thermallysprayed on the basis of a plasma spraying method, whereby the partitionwalls 22 and the spacer holders 30 formed of a thermal spray layer canbe formed on the exposed portions of the substratum 20. Almost nothermally sprayable material is deposited on the photosensitive dry film34. Then, before the photosensitive dry film 34 is removed, preferably,the partition walls 22 and the spacer holders 30 are polished to flattenthe top surfaces of the partition walls 22 and the spacer holders 30.The polishing can be carried out by wet polishing using a polishingpaper. Then, the photosensitive dry film 34 is removed, whereby astructure shown in FIG. 7(C) can be obtained. When the partition walls22 are constituted from an electrically conductive thermally sprayablematerial, the partition walls 22 work as a kind of network-shaped orstripe-shaped wiring, and the anode electrode 24 can be easilyisoelectrically controlled.

[Step-130]

Then, for forming a phosphor layer that emits light in red, phosphorparticles that emit light in red are dispersed, for example, inpolyvinyl alcohol (PVA) and water, ammonium bichromate is further added,and the thus-obtained phosphor slurry for emitting light in red isapplied to the entire surface. Then, the above phosphor slurry foremitting light in red is dried, exposed and developed, to form phosphorlayers 23R that emit light in red between predetermined partition walls22. The above procedures are carried out with regard to a phosphorslurry for emitting light in green and a phosphor slurry for emittinglight in blue, whereby the phosphor layers 23R that emit light in red,the phosphor layers 23G that emit light in green and phosphor layers 23Bthat emit light in blue are finally formed between predeterminedpartition walls 22 (see FIG. 7(D) and schematic partial layout drawingsof FIGS. 3 to 5).

[Step-140]

Then, on each phosphor layer 23 (phosphor layers 23R, 23G, 23B) isformed an intermediate film 25 formed of a lacquer constituted mainlyfrom an acrylic resin (see FIG. 8(A)). Specifically, the substratum 20having the phosphor layers 23 formed thereon is immersed in a watertank, a lacquer film is formed on the water surface, and the water inthe tank is withdrawn, whereby the intermediate layer 25 formed of thelacquer can be formed all over on the phosphor layer 23, the partitionwalls 22 and the spacer holders 30. The hardness and elongation ratio ofthe lacquer film can be modified depending upon the amount of aplasticizer to be added to the lacquer and conditions to be employedwhen the lacquer film is formed on the water surface, and these areoptimized, whereby the intermediate layer 25 can be formed all over onthe phosphor layer 23, the partition walls 22 and the spacer holders 30.The lacquer for constituting the intermediate layer 25 includes asolution of a cellulose derivative, generally a formulated materialcontaining nitrocellulose as a main component in a volatile solvent suchas a lower fatty acid ester, which is a kind of varnish in a broadsense, a urethane lacquer containing a synthetic polymer and an acryllacquer.

[Step-150]

Then, the anode electrode 24 made of aluminum is formed on the entiresurface by a vacuum vapor deposition method (see FIG. 8(B)). Finally,the intermediate layer 25 is fired by heat treatment at approximately400° C., whereby an anode panel AP having a structure shown in FIG. 8(C)can be obtained.

[Step-160]

On the other hand, there is prepared a cathode panel CP having electronemitting regions EA constituted from a plurality of field emissiondevices. On an insulating layer 12 is formed an electrically conductivelayer 16 having the form of a stripe and extending in parallel with thegate electrode 13 having the form of a stripe. The field emission devicewill be described in detail later. Then, the display is assembled.

[Step-160A]

That is, the spacer 31 having a low-melting-point metal material layer33A formed on the other surface 31A thereof is arranged in the firstpanel effective field. Specifically, the bottom portion (portion of thesurface 31A) of the spacer 31 is inserted between the spacer holders 30formed in the anode electrode AP and temporarily held.

[Step-160B]

Then, the low-melting-point metal material layer 33A is heated to meltit, whereby the spacer 31 is fixed to the first panel effective field.Specifically, the substratum 20 is heated to approximately 200 to 250°C. in a hot air furnace. In this manner, the low-melting-point metalmaterial layer 33A is melted, and after cooling, the spacer 31 can befixed to the first panel effective field.

[Step-160C]

Then, the second panel (cathode panel CP) is placed on the other topsurface 31B of the spacer 31, and then the first panel (anode panel AP)and the second panel (cathode panel CP) are bonded to each other intheir circumferential portions. Specifically, a frit glass for a bondinglayer is applied to bonding portions of the frame and cathode panel CP(more specifically, the supporting member 10) in advance, the cathodepanel CP (more specifically, the supporting substrate 10) and the frame(not shown) are attached and the frit glass is dried by preliminaryfiring, and then regular firing is carried out at approximately 390° C.for 10 to 30 minutes beforehand. And, a frit glass for a bonding layeris applied to bonding portions of the frame and the anode panel AP (morespecifically, the substratum 20), and the second panel (cathode panelCP) is placed on the other surface 31B of the spacer 31. In this case,the electrically conductive layer 16 formed in the cathode panel CP andthe low-melting-point metal material layer 33B are brought into contactwith each other, and the anode panel AP and the cathode panel CP arearranged such that the phosphor layer 23 and the electron emittingregion EA face each other. Then, the frit glass is dried by preliminaryfiring, and regular firing is carried out at approximately 390° C. for10 to 30 minutes. The low-melting-point metal material layer 33B ismelted, and the other top surface 31B of the spacer 31 is fixed to thecathode panel CP (more specifically, the electrically conductive layer16). On the other hand, the low-melting-point metal material layer 33Ais re-melted. After it is cooled, however, it substantially retains thestate it had before its re-melting. The state of the spacer 31 changesfrom a state where it is bonded to the first panel (anode panel AP) to astate where it is held with the spacer holders.

[Step-160D]

Then, the space surrounded by the anode panel AP, the cathode panel CP,the frame and the bonding layer is discharged through a through hole(not shown) and a chip tube (not shown), and when the pressure in thespace reaches approximately 10⁻⁴ Pa, the chip tube is sealed off byheat-melting. In this manner, the space surrounded by the anode panelAP, the cathode panel CP and the frame can be vacuumed. Then, necessarywiring to external circuits is carried out, to complete a so-calledthree-electrode type display.

In [Step-120], the partition walls 22 and the spacer holders 30 may beformed by an electric plating method instead of forming the partitionwalls 22 and the spacer holders 30 by the thermal spraying method. Inthis case, the partition walls 22 and the spacer holders 30 made, forexample, of nickel can be formed by an electric plating method using thelight-absorbing layer 21 as a cathode for plating and using, forexample, a nickel sulfamate solution. Further, an intermediate layermade of gold, silver or copper may be formed between the light-absorbinglayer 21 and the partition walls 22 and between the light-absorbinglayer 21 and the spacer holders 30. Alternatively, the partition walls22 and the spacer holders 30 can be also formed by a screen printingmethod, a method using a dispenser, a sand blasting method, a dry filmmethod or a photo-sensitive method.

Further, in [Step-160C], the frit glass can be replaced with a bondinglayer made from a low-melting-point metal material to bond the firstpanel (anode panel AP) and the second panel (cathode panel CP) in theircircumferential portions. Specifically, the circumferential portion ofthe second panel (cathode panel CP) and the frame are bonded in advancewith a second bonding layer made from a low-melting-point metalmaterial. And, the second panel (cathode panel CP) is placed on theother top surface 31B of the spacer 31, and the circumferential portionof the first panel (anode panel AP) and the frame are bonded with afirst bonding layer made from a low-melting-point metal material. InExamples to be described hereinafter, similarly, a first panel and asecond panel can be bonded to each other in their circumferentialportions with a bonding layer made from a low-melting-point metalmaterial in place of a frit glass. The low-melting-point metal materialfor constituting the low-melting-point metal material layer 33B and thefirst bonding layer is selected from low-melting-point metal materialshaving a lower melting point than any low-melting-point metal materialsconstituting the low-melting-point metal material layer 33A and thesecond bonding layer, and in this case, the re-melting of thelow-melting-point metal material 33A and the second bonding layer can besuppressed when the circumferential portion of the first panel (anodepanel AP) and the frame are bonded to each other.

The anode panel AP, the cathode panel CP and the frame are bondedtogether in a high vacuum atmosphere, or the anode panel AP and theframe are bonded together in a high vacuum atmosphere, and in this case,the space surrounded by the first panel (anode panel AP), the secondpanel (cathode panel CP), the frame and the bonding layer can be broughtinto a vacuum state at the same time. The same constitution may beemployed in Examples to be described hereinafter.

When the anode panel AP is read as a second panel, and when the cathodepanel CP is read as a first panel, a constitution corresponding to “Case24” in Table 1 is obtained, and a constitution corresponding to “Case44” in Table 2 is obtained.

The low-melting-point metal material layer 33B may not be formed on theother surface 31B of the spacer 31 which surface is opposed to thesecond panel (cathode panel CP). In this case, there are obtained aconstitution corresponding to “Case 2” in Table 1 and a constitutioncorresponding to “Case 32” in Table 2. Further, when the anode panel APis read as a second panel and when the cathode panel CP is read as afirst panel, there is obtained a constitution corresponding to “Case 14”in Table 1.

EXAMPLE 2

Example 2 is a variant of Example 1 and corresponds to “Case 22” inTable 1 and “Case 42” in Table 2 like Example 1. In Example 2, thespacer holders 30A for temporarily holding the spacer are formed on thecathode panel side. That is, the first panel is a cathode panel CPhaving a plurality of field emission devices formed thereon, and thesecond panel is an anode panel AP having the anode electrode 24 and thephosphor layer 23 formed thereon. FIG. 9 shows a schematic partial endview of a display having the above constitution in Example 2, and FIG.10 shows an enlarged schematic end view of part of the display. FIG. 9corresponds to an end view taken along arrows A-A in FIG. 3.

The cathode panel CP having the above structure can be manufactured bythe following method.

That is, the field emission devices are formed on a supporting member 10corresponding to the substratum. The method for manufacturing the fieldemission devices will be described in detail later. In addition thereto,an electrically conductive layer 16 having the form of a stripe andextending in parallel with the gate electrode 13 having the form of astripe is formed on an insulating layer 12 in advance. The electricallyconductive layer 16 having the form of a stripe is formed such that itis positioned between a pair of spacer holders 30A to be formedthereafter.

Then, an alkali-soluble photosensitive dry film having a thickness of 50μm is stacked on the entire surface, followed by exposure anddevelopment, whereby a mask (photosensitive dry film) having an openingis placed on the insulating layer 12, and portions where the spacerholders 30A are to be formed in the insulating layer 12 are exposed.Then, a thermally sprayable material made of chromium (Cr) (which is anelectrically conductive thermally sprayable material) is sprayed on thebasis of a plasma spraying method, whereby the spacer holders 30A formedof a thermally sprayed layer can be formed in exposed portions of theinsulating layer 12. Almost no thermally sprayable material is depositedon the photosensitive dry film. Before the photosensitive dry film isremoved, preferably, the spacer holders 30A are polished to flatten thetop surfaces of the space holders 30A. The polishing can be carried outby wet polishing using a polishing paper. Then, the photosensitive dryfilm is removed, and a structure shown in Tables 9 and 10 can be therebyobtained. Alternatively, the spacer holders 30A can be formed by aplating method in place of forming the spacer holders 30A by the thermalspraying method. In this case, the spacer holders 30A made, for example,of nickel can be formed by an electroless plating method or an electricplating method. Alternatively, the spacer holders 30A can be also formedby a screen printing method, a method using a dispenser, a dry filmmethod or a photo-sensitive method.

In Example 2, a step similar to [Step-160A] in Example 1 is employed,and in the step, a spacer 31 having a low-melting-point metal materiallayer 33A formed on the surface 31A thereof is arranged on the firstpanel effective field. Specifically, a bottom portion (part of thesurface 31A) of the spacer 31 is inserted between the spacer holders 30Aformed in the cathode panel CP and temporarily held. Thelow-melting-point metal material layer 33A comes into a state where itis in contact with the electrically conductive layer 16.

Then, in the same manner as in [Step-160B] of Example 1, thelow-melting-point metal material layer 33A is melted under heat to fixthe spacer 31 to the first panel effective field. Then, in the samemanner as in (Step-160C] of Example 1, the second panel (anode panel AP)is placed on the other surface 31B of the spacer 31, and then the firstpanel (cathode panel CP) and the second panel (anode panel AP) arebonded to each other in their circumferential portions. When the secondpanel (anode panel AP) is placed on the other surface 31B of the spacer31, the anode electrode 24 formed on the anode panel AP and thelow-melting-point metal material layer 33B are brought into contact witheach other, and the anode panel AP and the cathode panel CP are arrangedsuch that the phosphor layer 23 and the electron emitting region EA areopposed to each other. And, the anode panel AP and the cathode panel CP(more specifically, a substratum 20 and a supporting member 10) arebonded to each other in their circumferential portions through a frame(not shown).

Then, in the same manner as in [Step-160D] of Example 1, the spacesurrounded by the anode panel AP, the cathode panel CP, the frame andthe bonding layer is discharged through a through hole (not shown) and achip tube (not shown), and when the pressure in the space reachesapproximately 10⁻⁴ Pa, the chip tube is sealed off by heat-melting. Inthis manner, the space surrounded by the anode panel AP, the cathodepanel CP and the frame can be vacuumed. Then, necessary wiring toexternal circuits is carried out, to complete a so-calledthree-electrode type display.

When the cathode panel CP is read as a second panel, and when the anodepanel AP is read as a first panel, there is obtained a constitutioncorresponding to “Case 24” in Table 1 and there is obtained aconstitution corresponding to “Case 44” in Table 2.

The low-melting-point metal material layer 33B may not be formed on theother surface 31B of the spacer 31 which surface is opposed to thesecond panel (anode panel AP). In this case, there are obtained aconstitution corresponding to “Case 2” in Table 1 and a constitutioncorresponding to “Case 32” in Table 2. Further, when the cathode panelCP is read as a second panel and when the anode panel AP is read as afirst panel, there is obtained a constitution corresponding to “Case 14”in Table 1.

The spacer holders 30 shown in FIG. 1 and the spacer holders 30A shownin FIG. 9 may be combined. That is, the spacer holders 30 are formed inthe first panel (anode panel AP), the spacer holders 30A are formed inthe second panel (cathode panel CP) and the low-melting-point metalmaterial layers 33A and 33B are formed on both surfaces 31A and 31B ofthe spacer 31, and in this case, there are obtained a constitutioncorresponding to “Case 23” in Table 1 and a constitution correspondingto “Case 43” in Table 2. Alternatively, the spacer holders 30A areformed in the first panel (cathode panel CP), the spacer holders 30 areformed in the second panel (anode panel AP) and the low-melting-pointmetal material layers 33A and 33B are formed on both surfaces 31A and31B of the spacer 31, and in this case, there are obtained aconstitution corresponding to “Case 23” in Table 1 and a constitutioncorresponding to “Case 43” in Table 2. In these cases, further, thelow-melting-point metal material layer 33B may not be formed on theother surface 31B of the spacer 31 which surface is opposed to thesecond panel (cathode panel CP or anode panel AP), and in this case,there are obtained constitutions corresponding to “Case 3” in Table 1and “Case 33” in Table 2. Further, when the cathode panel CP is read asa second panel, and when the anode panel AP is read as a first panel,there is obtained a constitution corresponding to “Case 13” in Table 1.

EXAMPLE 3

Example 3 is also a variant of Example 1, and more specifically, it isdirected to a flat-type display according to the first constitution(“Case 1” in Table 1) and is also directed to the method formanufacturing a flat-type display, provided according to the firstaspect of the present invention (“Case 31” in Table 2).

In Example 3, a low-melting-point metal material layer 33A is formed onone surface 31A of the spacer 31 which surface is opposed to the firstpanel (anode panel AP), but no low-melting-point metal material layer33B is formed on the other surface 31B of the spacer 31 which surface isopposed to the second panel (cathode panel CP). In Example 3, further,neither partition walls nor spacer holders for temporarily holding thespacer are formed in the first panel (anode panel AP). Except for thesepoints, the display in Example 3 can be structured so as to be the sameas that of the display in Example 1, so that detailed explanationsthereof will be omitted. Further, the method for manufacturing the anodepanel AP can be the same as the method for manufacturing the anode panelAP, explained in Example 1, except that neither partition walls norspacer holders are formed, so that detailed explanations thereof will beomitted.

In Example 3, in a step similar to [Step-160] of Example 1, first, thespacer 31 is caused to stand in a predetermined position of the firstpanel (anode panel AP) by means of a positioning unit such as amicroscope and a robot, a vacuum adsorption apparatus, or the like. In astate where the spacer 31 is held with the robot, vacuum adsorptionapparatus, or the like, the low-melting-point metal material layer 33Aformed on the surface 31A of the spacer 31 is melted by a heating methodusing a laser, a lump, a hot air heater, or the like, to fix the spacer31 to the anode electrode 24 formed in the anode panel AP. Thisoperation may be carried out one by one or altogether simultaneouslywith regard to the spacers. Then, steps similar to [Step-160C] and[Step-160D] of Example 1 are carried out, whereby a display can beobtained.

In the step similar to [Step-160C] of Example 1, the second panel(cathode panel CP) is placed on the other surface 31B of the spacer 31,and then the first panel (anode panel AP) and the second panel (cathodepanel CP) are bonded to each other in their circumferential portions. Inthis case, the low-melting-point metal material layer 33A is re-melted,and the spacer 31 comes into a self-standing state from a state where itis bonded to the first panel (cathode panel AP). When an external forceis exerted laterally, the spacer may fall down. However, there can beemployed a method in which the first panel and the second panel do notmove during the process, such as a method using a batch type oven, andno spacer 31 falls down.

When the cathode panel CP is read as a first panel, and when the anodepanel AP is read as a second panel, there is obtained a constitutioncorresponding to “Case 11” in Table 1.

Further, the low-melting-point metal material layers 33A and 33B may beformed on both the surfaces 31A and 31B of the spacer 31 beforehand. Inthis case, there are obtained a constitution corresponding to “Case 21”in Table 1 and a constitution corresponding to “Case 41” in Table 2.

The anode panel AP (having no spacer holders) explained in Example 3 isemployed as a first panel, the cathode panel CP (having spacer holders)explained in Example 2 is employed as a second panel, thelow-melting-point metal material layer 33A is formed on one surface 31Aof the spacer 31 which surface is opposed to the first panel (anodepanel AP), and no low-melting-point metal material layer 33B is formedon the other surface 31B of the spacer 31 which surface is opposed tothe second panel (cathode panel CP). In this case, there are obtained aconstitution corresponding to “Case 4” in Table 1 and a constitutioncorresponding to “Case 34” in Table 2.

Further, the cathode panel CP (having no spacer holders) explained inExample 1 is employed as a first panel, the anode panel AP (havingspacer holders) explained in Example 1 is employed as a second panel,the low-melting-point metal material layer 33A is formed on one surface31A of the spacer 31 which surface is opposed to the first panel(cathode panel CP), and no low-melting-point metal material layer 33B isformed on the other surface 31B of the spacer 31 which surface isopposed to the second panel (anode panel AP). In this case, there areobtained a constitution corresponding to “Case 4” in Table 1 and aconstitution corresponding to “Case 34” in Table 2.

On the other hand, the cathode panel CP (having spacer holders)explained in Example 2 is employed as a first panel, the anode panel AP(having no spacer holders) explained in Example 3 is employed as asecond panel, no low-melting-point metal material layer is formed on onesurface 31A of the spacer 31 which surface is opposed to the first panel(anode panel AP), and the low-melting-point metal material layer 33B isformed beforehand on the other surface 31B of the spacer 31 whichsurface is opposed to the second panel (cathode panel CP). In this case,there is obtained a constitution corresponding to “Case 12” in Table 1.

Further, the anode panel AP (having spacer holders) explained in Example1 is employed as a first panel, the cathode panel CP (having no spacerholders) explained in Example 1 is employed as a second panel, nolow-melting-point metal material layer is formed on one surface 31A ofthe spacer 31 which surface is opposed to the first panel (anode panelAP), and the low-melting-point metal material layer 33B is formed on theother top surface 31B of the spacer 31 which top surface is opposed tothe second panel (cathode panel CP). In this case, there is obtained aconstitution corresponding to “Case 12” in Table 1.

EXAMPLE 4

Example 4 is concerned with the flat-type display of the presentinvention, more specifically to the flat-type display according to thefirst-C constitution (“Case 22” in Table 1), and it is further directedto the method for manufacturing a flat-type display, provided accordingto the second aspect of the present invention, more specifically to themethod for manufacturing a flat-type display according to the first 2Aand first 2B aspects of the present invention (“Case 62” in Table 2). InExample 4, the flat-type display is a cold cathode field emissiondisplay (display) as well.

The display of Example 4 (so-called three-electrode type display) issubstantially structurally the same as that of the display explained inExample 1, so that detailed explanations thereof will be omitted.

Like Example 1, a spacer 31 made of alumina (Al₂O₃) is arranged betweenthe first panel effective field and the second panel effective fieldwhich work as a display portion, and the spacer 31 is fixed to the firstpanel effective field and the second panel effective field with alow-melting-point metal material layer 133A and a low-melting-pointmetal material layer 133B made of Sn₆₀-Zn₄₀ (melting point 200 to 250°C.). More specifically, one surface 31A of the spacer 31 is fixed ontoan anode electrode 24 with the low-melting-point metal material layer133A, and the other surface 31B of the spacer 31 is fixed onto anelectrically conductive layer 16 having the form of a stripe with thelow-melting-point metal material layer 133B. The above electricallyconductive layer 16 having the form of a stripe is formed on aninsulating layer 12 and extends in parallel with a gate electrode 13having the form of a stripe. Conductive material layers 32A and 32B madeof titanium (Ti) are formed so as to coat both of the surfaces 31A and31B of the spacer 31.

The spacer 31 can be produced by forming a so-called green sheet, firingthe green sheet and cutting the thus-obtained green sheet fired product.The conductive material layers 32A and 32B made of Ti are formed so asto coat both the surfaces 31A and 31B of the spacer 31, for example, bya sputtering method.

The method for manufacturing a display in Example 4 shown in FIGS. 1 and3 will be explained below.

[Step-400]

First, steps similar to [Step-100] to [Step-150] are carried out.

[Step-410]

Then, a low-melting-point metal material layer 133A is formed in aportion where the spacer 31 is to be fixed in the first panel effectivefield. Specifically, the low-melting-point metal material layer 133A canbe formed in a portion where the spacer 31 is to be fixed in an anodeelectrode 24 by a vacuum vapor deposition method.

[Step-420]

On the other hand, there is prepared a cathode panel CP having electronemitting regions EA constituted of a plurality of field emissiondevices. On the insulating layer 12 is formed an electrically conductivelayer 16 having the form of a stripe and extending in parallel with agate electrode 13 having the form of a stripe. Further, the electricallyconductive layer 16 has a low-melting-point metal material layer 133Bformed thereon by a vacuum vapor deposition method. The field emissiondevices will be described in detail later. And, the display isassembled.

[Step-420A]

That is, the spacer 31 is arranged on the low-melting-point metalmaterial layer 133A. Specifically, the bottom portion of the spacer 31(part of the surface 31A) is inserted between spacer holders 30 fortemporarily holding the spacer which spacer holders are formed in theanode panel AP, and temporarily held. The low-melting-point metalmaterial layer 133A is formed between spacer holders 30, and thelow-melting-point metal material layer 133A and the conductive materiallayer 32A are in a state where they are in contact with each other.

[Step-420B]

Then, the low-melting-point metal material layer 133A is melted underheat to fix the spacer 31 to the first panel effective field.Specifically, a substratum 20 is heated to approximately 200 to 250° C.with a hot air furnace. By the above procedures, the low-melting-pointmetal material layer 133A is melted, and then, the low-melting-pointmetal material layer 133A is cooled, whereby the spacer 31 can be fixedto the first panel effective field.

[Step-430]

Then, a step similar to (Step-160C] of Example 1 is carried out to placethe second panel (cathode panel CP) on the other surface 31B of thespacer 31, and then the first panel (anode panel AP) and the secondpanel (cathode panel CP) are bonded to each other in theircircumferential portions. Then, a step similar to (Step-160D] of Example1 is carried out, to discharge the space surrounded by the anode panelAP, the cathode panel CP, the frame and the bonding layer through athrough hole (not shown) and a chip tube (not shown), and when thepressure in the space reaches approximately 10⁻⁴ Pa, the chip tube issealed off by heat-melting. In this manner, the space surrounded by theanode panel AP, the cathode panel CP and the frame can be vacuumed.Then, necessary wiring to external circuits is carried out, to completea so-called three-electrode type display.

When the anode panel AP is read as a second panel and when the cathodepanel CP is read as a first panel, there are obtained a constitutioncorresponding to “Case 24” in Table 1 and a constitution correspondingto “Case 64” in Table 2.

The low-melting-point metal material layer 133B may not be formed onthat portion of the second panel (cathode panel CP) which is opposed tothe other surface 31B of the spacer 31. In this case, there are obtaineda constitution corresponding to “Case 2” in Table 1 and a constitutioncorresponding to “Case 52” in Table 2. Further, when the anode panel APis read as a second panel and when the cathode panel CP is read as afirst panel, there is obtained a constitution corresponding to “Case 14”in Table 1.

EXAMPLE 5

Example 5 is a variant of Example 4, and like Example 4, Example 5 comesunder “Case 22” in Table 1 and “Case 62” in Table 2. In Example 5,spacer holders 30A for temporarily holding the spacer are formed on thecathode panel side. That is, the first panel is a cathode panel CPhaving a plurality of field emission devices formed therein, and thesecond panel is an anode panel AP having an anode electrode 24 and aphosphor layer 23 formed therein. The thus-constituted display ofExample 5 has substantially the same structure as the structure of thedisplay of Example 2 shown in FIGS. 9 and 10.

The cathode panel CP having the above structure can be manufactured bythe following method.

That is, first, field emission devices are formed on a supporting member10 corresponding to the substratum. The method for manufacturing thefield emission devices will be described in detail later. Anelectrically conductive layer 16 having the form of a stripe andextending in parallel with a gate electrode 13 having the form of astripe is formed on the insulating layer 12 beforehand. The electricallyconductive layer 16 having the form of a stripe is formed such that itis positioned between a pair of spacer holders 30A to be formedthereafter. Further, a low-melting-point metal material layer 133A isformed on the electrically conductive layer 16 beforehand by a vacuumvapor deposition method.

Then, an alkali-soluble photosensitive dry film having a thickness of 50μm is stacked on the entire surface, followed by exposure anddevelopment, to arrange a mask (photosensitive dry film) having anopening on the insulating layer 12, and a portion where the spacerholders 30A are to be formed on the insulating layer 12 is exposed.Then, a thermally sprayable material made of chromium (Cr) (that is anelectrically conductive thermally sprayable material) is thermallysprayed, for example, on the basis of a plasma spraying method, wherebythe spacer holders 30A formed of the thermally sprayed layer can beformed on the exposed portion of the insulating layer 12. Almost nothermally sprayable material is deposited on the photosensitive dryfilm. Then, before the photosensitive dry film is removed, preferably,the spacer holders 30A are polished to flatten the top surfaces of thespacer holders 30A. The polishing can be carried out by wet polishingusing a polishing paper. Then, the photosensitive dry film is removed.Alternatively, the spacer holders 30A can be also formed by a platingmethod instead of forming the spacer holders 30A by a thermal sprayingmethod. In this case, the spacer holders 30A made, for example, ofnickel can be formed by an electroless plating method and an electricplating method. Alternatively, the spacer holders 30A can be also formedby a screen printing method, a method using a dispenser, a dry filmmethod or a photo-sensitive method.

In Example 5, in a step similar to [Step-420A) of Example 4, a spacer 31is arranged on the first panel effective field. Specifically, the bottomportion of the spacer 31 (part of surface 31A) is inserted between thespacer holders 30A formed in the cathode panel CP and temporarily held.The low-melting-point metal material layer 133A and a conductivematerial layer 32A are in a state where they are in contact with eachother.

Then, in the same manner as in [Step-420B] of Example 4, thelow-melting-point metal material layer 133A is melted under heat to fixthe spacer 31 to the first panel effective field.

Then, in the same manner as in [Step-430] of Example 4, the second panel(anode panel AP) is placed on the other surface 31B of the spacer 31,and then the first panel (cathode panel CP) and the second panel (anodepanel AP) are bonded to each other in their circumferential portions.When the second panel (anode panel AP) is placed on the other surface31B of the spacer 31, the anode electrode 24 formed in the anode panelAP and the low-melting-point metal material layer 133B are brought intocontact with each other, and the anode panel AP and the cathode panel CPare arranged such that the phosphor layer 23 and the electron emittingregion EA are opposed to each other. And, the anode panel AP and thecathode panel CP (more specifically, the substratum 20 and thesupporting member 10) are bonded to each other through a frame (notshown) in their circumferential portions.

Then, in the same manner as in (Step-430] of Example 4, the spacesurrounded by the anode panel AP, the cathode panel CP, the frame andthe bonding layer is discharged through a through hole (not shown) and achip tube (not shown), and when the pressure in the space reachesapproximately 10⁻⁴ Pa, the chip tube is sealed off by heat-melting. Inthis manner, the space surrounded by the anode panel AP, the cathodepanel CP and the frame can be vacuumed. Then, necessary wiring toexternal circuits is carried out, to complete a so-calledthree-electrode type display.

When the cathode panel CP is read as a second panel, and when the anodepanel AP is read as a first panel, there are obtained a constitutioncorresponding to “Case 24” in Table 1 and a constitution correspondingto “Case 64” in Table 2.

The low-melting-point metal material layer 133B may not be formed onthat portion of the second panel (anode panel AP) which is opposed tothe other surface 31B of the spacer 31. In this case, there are obtaineda constitution corresponding to “Case 2” in Table 1 and a constitutioncorresponding to “Case 52” in Table 2. In this case, further, when thecathode panel CP is read as a second panel and when the anode panel APis read as a first panel, there is obtained a constitution correspondingto “Case 14” in Table 1.

The spacer holders 30 shown in FIG. 1 and the spacer holders 30A shownin FIG. 9 may be combined. That is, the spacer holders 30 are formed inthe first panel (anode panel AP), the spacer holders 30A are formed inthe second panel (cathode panel CP), and the low-melting-point metalmaterial layers 133A and 133B are formed in portions where the spacer 31is to be fixed in the first panel effective field and the second paneleffective field. In this case, there are obtained a constitutioncorresponding to “Case 23” in Table 1 and a constitution correspondingto “Case 63” in Table 2. Alternatively, the spacer holders 30A areformed in the first panel (cathode panel CP), the spacer holders 30 areformed in the second panel (anode panel AP) and the low-melting-pointmetal material layers 133A and 133B are formed in portions where thespacer 31 is to be fixed in the first panel effective field and thesecond panel effective field. In this case, there is obtained aconstitution corresponding to “Case 23” in Table 1 and a constitutioncorresponding to “Case 63” in Table 2. The low-melting-point metalmaterial layer 133B may not be formed on a portion where the spacer 31is to be fixed in the second panel effective field (part of theeffective field of the cathode panel CP or the anode panel AP). In thiscase, there are obtained a constitution corresponding to “Case 3” inTable 1 and a constitution corresponding to “Case 53” in Table 2.Further, when the cathode panel CP or the anode panel AP is read as asecond panel, and when the anode panel AP or the cathode panel CP isread as a first panel, there is obtained a constitution corresponding to“Case 13” in Table 1.

EXAMPLE 6

Example 6 is also a variant of Example 4. More specifically, it isdirected to the flat-type display according to the first constitution(“Case 1” in Table 1), and it is also directed to the method formanufacturing a flat-type display, provided according to the secondaspect of the present invention (Case 51 in Table 2).

In Example 6, the low-melting-point metal material layer 133A is formedin that portion of the fist panel (anode panel AP) which is opposed toone surface 31A of the spacer 31, but the low-melting-point metalmaterial layer 133B is not formed on that portion of the second panel(cathode panel CP) which is opposed to the other surface 31B of thespacer 31. In Example 6, further, the partition walls and the spacerholders for temporarily holding the spacer are not formed in the firstpanel (anode panel AP). Except for these points, the structure of thedisplay of Example 6 can be the same as the structure of the display ofExample 4, so that detailed explanations thereof will be omitted.Further, the method for manufacturing the anode panel AP can be the sameas the method for manufacturing the anode panel AP explained in Example1 except that the partition walls and the spacer holders are not formed,so that detailed explanations thereof will be omitted.

In Example 6, in a step similar to [Step-420A] of Example 4, first, thespacer 31 is caused to stand in a predetermined position of the firstpanel (anode panel AP) by means of a positioning unit such as amicroscope and a robot, a vacuum adsorption apparatus, or the like. In astate where the spacer 31 is held with the robot, vacuum adsorptionapparatus, or the like, the low-melting-point metal material layer 133Aformed in the first panel effective field is melted by a heating methodusing a laser, a lump, a hot air heater, or the like, to fix the spacer31 to the anode electrode 24 formed in the anode panel AP. Thisoperation may be carried out one by one or altogether simultaneouslywith regard to all of the spacers. Then, steps similar to [Step-420B]and [Step-430] of Example 4 are carried out, whereby a display can beobtained.

When the cathode panel CP is read as a first panel and when the anodepanel AP is read as a second panel, there is obtained a constitutioncorresponding to “Case 11” in Table 1.

The low-melting-point metal material layers 133A and 133B may be formedin portions where the spacer 31 is to be fixed in the first paneleffective field and the second panel effective field. In this case,there are obtained a constitution corresponding to “Case 21” in Table 1and a constitution corresponding to “Case 61” in Table 2.

The anode panel AP (having no spacer holders) explained in Example 6 isemployed as a first panel, the cathode panel CP (having the spacerholders) explained in Example 5 is employed as a second panel, thelow-melting-point metal material layer 133A is formed beforehand in aportion where the spacer 31 is to be fixed in the first panel effectivefield, and the low-melting-point metal material layer 133B is not formedin a portion where the spacer is to be fixed in the second paneleffective field. In this case, there are obtained a constitutioncorresponding to “Case 4” in Table 1 and a constitution corresponding to“Case 54” in Table 2.

The cathode panel CP (having no spacer holders) explained in Example 4is used as a first panel, the anode panel AP (having spacer holders)explained in Example 4 is used as a second panel, the low-melting-pointmetal material layer 133A is formed beforehand in a portion where thespacer is to be fixed in the first panel effective field, and thelow-melting-point metal material layer 133B is not formed in a portionwhere the spacer is to be fixed in the second panel effective field. Inthis case, there are obtained a constitution corresponding to “Case 4”in Table 1 and a constitution corresponding to “Case 54“ in Table 2.

On the other hand, the cathode panel CP (having spacer holders)explained in Example 5 is used as a first panel, the anode panel AP(having no spacer holders) explained in Example 6 is used as a secondpanel, the low-melting-point metal material layer is not formed in aportion where the spacer 31 is to be fixed in the first panel effectivefield, and the low-melting-point metal material layer 133B is formed ina portion where the spacer 31 is to be fixed in the second paneleffective field. In this case, there is obtained a constitutioncorresponding to “Case 12” in Table 1.

Further, the anode panel AP (having spacer holders) explained in Example4 is used as a first panel, the cathode panel CP (having no spacerholders) explained in Example 4 is used as a second panel, thelow-melting-point metal material layer is not formed in a portion wherethe spacer 31 is to be formed in the first panel effective field, andthe low-melting-point metal material layer 133B is formed in a portionwhere the spacer 31 is to be fixed in the second panel effective field.In this case, there is obtained a constitution corresponding to “Case12” in Table 1.

EXAMPLE 7

In Example 7, various variants of the spacer and the spacer holders willbe explained.

In an example having a schematic drawing of FIG. 11(A) obtained byviewing the spacer 31 from its top surface side, having a schematicdrawing of FIG. 11(B) showing the layout of the spacer holders 30 andhaving a schematic drawing of FIG. 11(C) showing a state where thespacer 31 is held with the spacer holders 30, a plurality of the spacerholders 30 constituting each group of the spacer holders are positionedon a straight line L (see FIG. 11(B)). Further, the spacer 31 held witha plurality of the spacer holders 30 in the group of spacer holders isarranged between the second panel effective field and the first paneleffective field which work as a display portion. Specifically, thebottom portion (top surface) of the spacer 31 is inserted between spacerholder 30 and spacer holder 30. And, as shown in FIG. 11(A), the spacer31 is curbed along its longitudinal direction before it is arrangedbetween the first panel effective field and the second panel effectivefield. In the example shown in FIGS. 11(B) and 11(C), there is shown astate where the group of spacer holders is constituted of three spacerholders 30, and the spacer 31 is held with the three spacer holder 30.However, the number of the spacer holders 30 for holding the spacer 31(or the number of the spacer holders constituting the group of spacerholders) is not limited to three.

In the spacer 31 before it was arranged between the first paneleffective field and the second panel effective field, the distance L₂from an imaginary line L_(IMG) connecting both ends of the spacer 31 tothe central portion of the spacer 31 was determined to be 0.3 mm.Further, in the spacer before it was arranged between the first paneleffective field and the second panel effective field, it was determinedthat 5×10⁻⁴L₁=L₂ in which L₁ was a distance between both ends of thespacer and L₂ was a distance from an imaginary line connecting both endsof the spacer to the central portion of the spacer. Further, the spacer31 had a length of 100 mm, a thickness of 50 μm and a height of 1 mm.When the spacer 31 is cut with an imaginary plane at right angles withits longitudinal direction, the spacer 31 has a cross-sectional form ofa long and narrow rectangle.

The spacer 31 is constituted of ceramics made of alumina. The spacer 31can be produced by forming a so-called green sheet, firing the greensheet and cutting the resultant green sheet fired product. Before orafter the green sheet fired product is cut, both surfaces of the greensheet fired product are polished to make the surface roughness of oneside surface of the spacer 31 different from the surface roughness ofthe other side surface, whereby a curved state can be obtained.Alternatively, a strain-generating layer made, for example, of Si₃N₄ maybe formed on one surface of the green sheet fired product before orafter it is cut. The method of forming the strain-generating layerincludes a known PVD method and CVD method.

FIGS. 12(A) and 12(B) show another variant example of the spacer andspacer holders. FIG. 12(A) schematically shows the layout of spacerholders 130, and FIG. 12(B) schematically shows a state where the spacer131 is held with the spacer holders 130. In FIGS. 12(A) and 12(B), agroup of the spacer holders is constituted of three spacer holders 130,and the spacer 131 is held with these three spacer holders 130. However,the number of the spacer holders 130 for holding the spacer 131 (or thenumber of the spacer holders constituting the group of spacer holders)is not limited to three. In this example, a plurality of the spacerholders 130 constituting each group of spacer holders are not positionedon a straight line, as is shown in FIG. 12(A).

The spacer 131 held with the plurality of the spacer holders 130 in thegroup of spacer holders are arranged between the second panel effectivefield and the first panel effective field which work as a displayportion. Specifically, the bottom portion of the spacer 131 is insertedbetween spacer holder 130 and spacer holder 130. Before the spacer 131is arranged between the first panel effective field and the second paneleffective field, the spacer 131 may be curved along its longitudinaldirection (see FIG. 11(A)), or may not be curved.

End portions of some of partition walls 22 have the form of a letter“T”, and the horizontal bar portion of the letter “T” corresponds tospacer holder 130. The spacer holders 130 were provided at intervals of1 mm along an imaginary line L_(IMG). Further, the distance between eachpair of the spacer holders 130 was 55 μm, and the spacer holders 130 hada height of approximately 50 μm. There may be employed a constitution inwhich some of the partition walls 22 are provided with projectionportions, and the spacer holders are constituted from these projectionportions. Further, the spacer holders 130 may be formed separately fromthe partition walls 22. The distance L₂ from the imaginary line L_(IMG)connecting spacer holders positioned at one end of the group of thespacer holders and spacer holders positioned at the other end of thegroup of the spacer holder to the central portion of an imaginary line(first imaginary line) C_(IMG) connecting a plurality of the spacerholders constituting the above group of the spacer holders wasdetermined to be 50 μm.

The spacer 131 is constituted of ceramics made of alumina. The spacer131 can be produced by forming a so-called green sheet, firing the greensheet and cutting the resultant green sheet fired product. Before orafter the green sheet fired product is cut, both surfaces of the greensheet fired product may be polished to make the surface roughness of oneside surface of the spacer 31 different from the surface roughness ofthe other side surface, to obtain a curved state. Alternatively, astrain-generating layer made, for example, of Si₃N₄ may be formed on onesurface of the green sheet fired product before or after it is cut. Themethod of forming the strain-generating layer includes a known PVDmethod and CVD method. In these cases, however, the spacer before heldwith the group of spacer holders is required to have a curved state thatis directionally opposite to the curved state of the first imaginaryline C_(IMG) connecting a plurality of the spacer holders constitutingthe group of spacer holders formed in the first panel effective field.Alternatively, the spacer before held with a group of the spacer holdersmay have the form of a straight line along its longitudinal direction.

The spacer 131 was determined to have a length of 100 mm, a thickness of50 μm and a height of 1 mm. When the spacer 131 was cut with animaginary plane at right angles with its longitudinal direction, thespacer 131 had the cross-sectional form of a long and narrow rectangle.In the spacer 131 that was arranged between the first panel effectivefield and the second panel effective field, the distance from theimaginary line connecting both ends of the spacer 131 to the centralportion of the spacer 131 was 50 μm. Alternatively, In the spacer 131that was arranged between the first panel effective field and the secondpanel effective field, L₂=5×10⁻⁴L₁ in which L₁ was a distance betweenboth ends of the spacer 131 and L₂ was a distance from the imaginaryline connecting both end of the spacer 131 to the central portion of thespacer 131.

EXAMPLE 8

In Example 8, various field emission devices and methods formanufacturing them will be explained.

A field emission device constituting a so-called three-electrodes-typecold cathode field emission display can be specifically classified, forexample, into the following two categories depending upon the structureof the electron-emitting portion. That is, a field emission devicehaving a first structure comprises;

(A) a stripe-shaped cathode electrode which is formed on a supportingmember and extends in a first direction,

(B) an insulating layer formed on the supporting member and the cathodeelectrode,

(C) a stripe-shaped gate electrode which is formed on the insulatinglayer and extends in a second direction different from the firstdirection,

(D) a first opening portion formed in the gate electrode and a secondopening portion formed in the insulating layer and communicating withthe first opening portion, and

(E) an electron-emitting portion formed on the cathode electrodepositioned in the bottom portion of the second opening portion, and

said field emission device has a structure in which theelectron-emitting portion exposed in the bottom portion of the secondopening portion is for emitting electrons.

The field emission device having the above first structure includes theabove-mentioned Spindt-type field emission device (field emission devicehaving a conical electron-emitting portion formed on the cathodeelectrode positioned in the bottom portion of the second openingportion), and a plane-type field emission device (field emission devicehaving a nearly flat electron-emitting portion formed on the cathodeelectrode positioned in the bottom portion of the second openingportion).

A field emission device having a second structure comprises;

(A) a stripe-shaped cathode electrode which is formed on a supportingmember and extends in a first direction,

(B) an insulating layer formed on the supporting member and the cathodeelectrode,

(C) a stripe-shaped gate electrode which is formed on the insulatinglayer and extends in a second direction different from the firstdirection, and

(D) a first opening portion formed in the gate electrode and a secondopening portion formed in the insulating layer and communicating withthe first opening portion, and

said field emission device has a structure in which a portion of thecathode electrode, which portion is exposed in the bottom portion of thesecond opening portion, corresponds to the electron-emitting portion andthe portion of the cathode electrode, which portion is exposed in thebottom portion of the second opening portion, and is for emittingelectrons.

The field emission device having the above second structure includes aflat-type field emission device which emits electrons from the flatsurface of the cathode electrode.

In the Spindt-type field emission device, the material for constitutingan electron-emitting portion may include at least one material selectedfrom the group consisting of tungsten, a tungsten alloy, molybdenum, amolybdenum alloy, titanium, a titanium alloy, niobium, a niobium alloy,tantalum, a tantalum alloy, chromium, a chromium alloy andimpurity-containing silicon (polysilicon or amorphous silicon). Theelectron-emitting portion of the Spindt-type field emission device canbe formed by, for example, a vacuum vapor deposition method, asputtering method and a CVD method.

In the plane-type field emission device, preferably, theelectron-emitting portion is made of a material having a smaller workfunction Φ than a material for constituting a cathode electrode. Thematerial for constituting an electron-emitting portion can be selectedon the basis of the work function of a material for constituting acathode electrode, a potential difference between the gate electrode andthe cathode electrode, a required current density of emitted electrons,and the like. Typical examples of the material for constituting acathode electrode of the field emission device include tungsten (Φ=4.55eV), niobium (Φ=4.02-4.87 eV), molybdenum (Φ=4.53-4.95 eV), aluminum(Φ=4.28 eV), copper (Φ=4.6 eV), tantalum (Φ=4.3 eV), chromium (Φ=4.5 eV)and silicon (Φ=4.9 eV). The material for constituting anelectron-emitting portion preferably has a smaller work function Φ thanthese materials, and the value of the work function thereof ispreferably approximately 3 eV or smaller. Examples of such a materialinclude carbon (Φ<1 eV), cesium (Φ=2.14 eV), LaB₆ (Φ=2.66-2.76 eV), BaO(Φ=1.6-2.7 eV), SrO (Φ=1.25-1.6 eV), Y₂O₃ (Φ=2.0 eV), CaO (Φ=1.6-1.86eV), BaS (Φ=2.05 eV), TiN (Φ=2.92 eV) and ZrN (Φ=2.92 eV). Morepreferably, the electron-emitting portion is made of a material having awork function Φ of 2 eV or smaller. The material for constituting anelectron-emitting portion is not necessarily required to have electricconductivity.

Otherwise, in the plane-type field emission device, the material forconstituting an electron-emitting portion can be selected from materialshaving a secondary electron gain δ greater than the secondary electrongain δ of the electrically conductive material for constituting acathode electrode. That is, the above material can be properly selectedfrom metals such as silver (Ag), aluminum (Al), gold (Au), cobalt (Co),copper (Cu), molybdenum (Mo), niobium (Nb), nickel (Ni), platinum (Pt),tantalum (Ta), tungsten (W) and zirconium (Zr); semiconductors such assilicon (Si) and germanium (Ge); inorganic simple substances such ascarbon and diamond; and compounds such as aluminum oxide (Al₂O₃), bariumoxide (BaO), beryllium oxide (BeO), calcium oxide (CaO), magnesium oxide(MgO), tin oxide (SnO₂), barium fluoride (BaF₂) and calcium fluoride(CaF₂). The material for constituting an electron-emitting portion isnot necessarily required to have electric conductivity.

In the plane-type field emission device, as a material for constitutingan electron-emitting portion, particularly, carbon is preferred. Morespecifically, diamond, graphite and a carbon nano-tube structure arepreferred. When the electron-emitting portion is made of diamond,graphite or a carbon nano-tube structure, an emitted-electron currentdensity necessary for the display can be obtained at an electric fieldintensity of 5×10⁷ V/m or lower. Further, since diamond is an electricresister, emitted-electron currents obtained from the electron-emittingportions can be brought into uniform currents, and the fluctuation ofluminescence efficiency can be suppressed when such field emissiondevices are incorporated into the display. Further, since the abovematerials exhibit remarkably high durability against sputtering by ionsof residual gas in the display, field emission devices having a longerlifetime can be attained.

Specifically, the carbon nano-tube structure includes a carbon nano-tubeand a carbon nano-fiber. More specifically, the electron-emittingportion may be constituted of a carbon nano-tube, it may be constitutedof a carbon nano-fiber, or it may be constituted of a mixture of acarbon nano-tube with a carbon nano-fiber. Macroscopically, the carbonnano-tube and carbon nano-fiber may have the form of a powder or a thinfilm. The carbon nano-tube structure may have the form of a cone in somecases. The carbon nano-tube and carbon nano-fiber can be produced orformed by a known PVD method such as an arc discharge method and a laserabrasion method; and any one of various CVD methods such as a plasma CVDmethod, a laser CVD method, a thermal CVD method, a gaseous phasesynthetic method and a gaseous phase growth method.

The plane-type field emission device can be produced by a method inwhich a dispersion of a carbon nano-tube structure in a binder materialis, for example, applied onto a desired region of the cathode electrodeand the binder material is fired or cured (more specifically, a methodin which the carbon nano-tube structure is dispersed in an organicbinder material such as an epoxy resin or an acrylic resin or aninorganic binder material such as water glass, the dispersion is, forexample, applied onto a desired region of the cathode electrode, then,the solvent is removed and the binder material is fired and cured). Theabove method will be referred to as “first forming method of a carbonnano-tube structure”. The application method includes, for example, ascreen printing method.

Alternatively, the plane-type field emission device can be produced by amethod in which a dispersion of the carbon nano-tube structure in ametal compound solution is applied onto the cathode electrode and then,the metal compound is fired, whereby the carbon nano-tube structure isfixed to the surface of the cathode electrode with a matrix containingmetal atoms constituting the metal compound. The above method will bereferred to as “second forming method of a carbon nano-tube structure”.The matrix is preferably constituted of an electrically conductive metaloxide. More specifically, it is preferably constituted of tin oxide,indium oxide, indium-tin oxide, zinc oxide, antimony oxide orantimony-tin oxide. After the firing, there can be obtained a statewhere part of each nano-tube structure is embedded in the matrix, orthere can be obtained a state where the entire portion of each carbonnano-tube is embedded in the matrix. The matrix preferably has a volumeresistivity of 1×10⁻⁹ Ω·m to 5×10⁻⁶Ω·m.

The metal compound for constituting the metal compound solutionincludes, for example, an organometal compound, an organic acid metalcompound and metal salts (for example, chloride, nitrate and acetate).The organic acid metal compound solution is, for example, a solutionprepared by dissolving an organic tin compound, an organic indiumcompound, an organic zinc compound or an organic antimony compound in anacid (for example, hydrochloric acid, nitric acid or sulfuric acid) anddiluting the resultant solution with an organic solvent (for example,toluene, butyl acetate or isopropyl alcohol). Further, the organic metalcompound solution is, for example, a solution prepared by dissolving anorganic tin compound, an organic indium compound, an organic zinccompound or an organic antimony compound in an organic solvent (forexample, toluene, butyl acetate or isopropyl alcohol). When the amountof the solution is 100 parts by weight, the solution preferably has acomposition containing 0.001 to 20 parts by weight of the carbonnano-tube structure and 0.1 to 10 parts by weight of the metal compound.The solution may contain a dispersing agent and a surfactant. From theviewpoint of increasing the thickness of the matrix, an additive such ascarbon black or the like may be added to the metal compound solution. Insome cases, the organic solvent may be replaced with water.

The method for applying, onto the cathode electrode, the metal compoundsolution in which the carbon nano-tube structure is dispersed includes aspray method, a spin coating method, a dipping method, a die quartermethod and a screen printing method. Of these, a spray method ispreferred in view of easiness in application.

There may be employed a constitution in which the metal compoundsolution in which the carbon nano-tube structure is dispersed is appliedonto the cathode electrode, the metal compound solution is dried to forma metal compound layer, then, an unnecessary portion of the metalcompound layer on the cathode electrode is removed, and then the metalcompound is fired. Otherwise, an unnecessary portion of the metalcompound layer on the cathode electrode may be removed after the metalcompound is fired. Otherwise, the metal compound solution may be appliedonly onto a desired region of the cathode electrode.

The temperature for firing the metal compound is preferably, forexample, a temperature at which the metal salt is oxidized to form ametal oxide having electric conductivity, or a temperature at which theorganometal compound or an organic acid metal compound is decomposed toform a matrix (for example, a metal oxide having electric conductivity)containing metal atoms constituting the organometal compound or theorganic acid metal compound. For example, the above temperature ispreferably at least 300° C. The upper limit of the firing temperaturecan be a temperature at which elements constituting the field emissiondevice or the cathode panel do not suffer any thermal damage and thelike.

In the first forming method or the second forming method of a carbonnano-tube structure, it is preferred to carry out a kind of anactivation treatment (washing treatment) of the surface of theelectron-emitting portion, since the efficiency of emission of electronsfrom the electron-emitting portion is further improved. The aboveactivation treatment includes a plasma treatment in an atmospherecontaining a gas such as hydrogen gas, ammonia gas, helium gas, argongas, neon gas, methane gas, ethylene gas, acetylene gas or nitrogen gas.

In the first forming method or the second forming method of a carbonnano-tube structure, the electron-emitting portion may be formed in thatportion of the cathode electrode which is positioned in a bottom portionof the second opening portion, or the electron-emitting portion may bealso formed so as to extend from that portion of the cathode electrodewhich is positioned in a bottom portion of the second opening portion toa surface of that portion of the cathode electrode which is differentfrom the cathode electrode portion in the bottom portion of the secondopening portion. Further, the electron-emitting portion may be formed onthe entire surface or part of the surface of that portion of the cathodeelectrode that is positioned in the bottom portion of the second openingportion.

In the various field emission device, the material for constituting acathode electrode can be selected from metals such as tungsten (W),niobium (Nb), tantalum (Ta), titanium (Ti), molybdenum (Mo), chromium(Cr), aluminum (Al) and copper (Cu), gold (Au), silver (Ag) and thelike; alloys and compounds containing these metal elements (for example,nitrides such as TiN and silicides such as WSi₂, MoSi₂, TiSi₂ andTaSi₂); semiconductors such as silicon (Si); carbon thin film such asdiamond; and indium-tin oxide (ITO). Although not specially limited, thethickness of the cathode electrode is approximately 0.05 to 0.5 μm,preferably 0.1 to 0.3 μm.

In the various field emission devices, the conductive material forconstituting the gate electrode includes at least one metal selectedfrom the group consisting of tungsten (W), niobium (Nb), tantalum (Ta),titanium (Ti), molybdenum (Mo), chromium (Cr), aluminum (Al), copper(Cu), gold (Au), silver (Ag), nickel (Ni), cobalt (Co), zirconium (Zr),iron (Fe), platinum (Pt) and zinc (Zn); alloys or compounds containingthese metal elements (for example, nitrides such as TiN and silicidessuch as WSi₂, MoSi₂, TiSi₂ and TaSi₂); semiconductors such as silicon(Si); and electrically conductive metal oxides such as indium-tin oxide(ITO), indium oxide and zinc oxide. In addition, the electricallyconductive layer may be constituted of the same material as the materialfor constituting the gate electrode.

The method for forming the cathode electrode and the gate electrode andthe electrically conductive layer includes deposition methods such as anelectron beam deposition method and a hot filament deposition method, asputtering method, a combination of a CVD method or an ion platingmethod with an etching method, a screen-printing method, a platingmethod and a lift-off method. When a screen-printing method or a platingmethod is employed, the cathode electrodes in the form of stripes can bedirectly formed.

In the field emission device having the first or second structure,depending upon the structure of field emission device, oneelectron-emitting portion may exist in one first opening portion formedin the gate electrode and one second opening portion formed in theinsulating layer, or a plurality of electron-emitting portions may existin one first opening portion formed in the gate electrode and one secondopening portion formed in the insulating layer, or one electron-emittingportion or a plurality of electron-emitting portions may exist in aplurality of first opening portions formed in the gate electrode and onesecond opening portion which is formed in the insulating layer andcommunicates with such first opening portions.

The plane form of the first or second opening portion (form obtained bycutting the first or second opening portion with an imaginary plane inparallel with the supporting member surface) may be any form such as acircle, an oval, a rectangle, a polygon, a rounded rectangle or arounded polygon. The first opening portion can be formed, for example,by isotropic etching or by a combination of anisotropic etching andisotropic etching. The first opening portion can be directly formeddepending upon the forming method of the gate electrode. The secondopening portion can also be formed, for example, by isotropic etching orby a combination of anisotropic etching and isotropic etching.

In the field emission device having the first structure, a resistancelayer may be formed between the cathode electrode and theelectron-emitting portion. Otherwise, when the surface of the cathodeelectrode corresponds to the electron-emitting portion (that is, in thefield emission device having the second structure), the cathodeelectrode may have a three-layered structure constituted of anelectrically conductive material layer, a resistance layer and anelectron-emitting layer corresponding to the electron-emitting portion.The resistance layer can stabilize performances of the field emissiondevice and can attain uniform electron-emitting properties. The materialfor constituting a resistance layer includes carbon-containing materialssuch as silicon carbide (SiC) and SiCN; SiN; semiconductor materialssuch as amorphous silicon and the like; and refractory metal oxides suchas ruthenium oxide (RuO₂), tantalum oxide and tantalum nitride. Theresistance layer can be formed by a sputtering method, a CVD method or ascreen-printing method. The resistance value of the resistance layer isapproximately 1×10⁵ to 1×10⁷Ω, preferably several MΩ.

As a material for constituting an insulating layer, SiO₂-containingmaterial such as SiO₂, BPSG, PSG, BSG, AsSG, PbSG, SiN, SiON and spin onglass (SOG), low melting-point glass and a glass paste, SiN, aninsulating resin such as polyimide and the like can be used alone or incombination. The insulating layer can be formed by a known method suchas a CVD method, an application method, a sputtering method or a screenprinting method.

[Spindt-Type Field Emission Device]

The Spindt-type field emission device comprises:

(a) a stripe-shaped cathode electrode 11 being formed on a supportingmember 10 and extending in a first direction,

(b) an insulating layer 12 formed on the supporting member 10 and thecathode electrode 11,

(c) a stripe-shaped gate electrode 13 being formed on the insulatinglayer 12 and extending in a second direction different from the firstdirection,

(d) a first opening portion 14A formed through the gate electrode 13 anda second opening portion 14B being formed through the insulating layer12 and communicating with the first opening portion 14A, and

(e) an electron-emitting portion 15 formed on a cathode electrode 11positioned in the bottom portion of the second opening portion 14B, and

has a structure in which electrons are emitted from the conicalelectron-emitting portion 15 exposed in the bottom portion of the secondopening portion 14B.

The method of manufacturing the Spindt-type field emission device willbe explained below with reference to FIGS. 13(A), 13(B), 14(A) and 14(B)which are schematic partial end views of the supporting member 10, etc.,constituting a cathode panel.

The above Spindt-type field emission device can be obtained basically bya method in which the conical electron-emitting portion 15 is formed byvertical vapor deposition of a metal material. That is, while depositionparticles perpendicularly enter the first opening portion 14A formedthrough the gate electrode 13, the amount of deposition particlesreaching the bottom portion of the second opening portion 14B isgradually decreased by utilizing a masking effect produced by anoverhanging deposit formed around the edge of the opening of the firstopening portion 14A, and the electron-emitting portion 15, which is aconical deposit, is formed in a self-alignment manner. There will beexplained below a method in which a peeling-off layer 17A is formed onthe gate electrode 13 and the insulating layer 12 beforehand for makingit easy to remove an unnecessary overhanging deposit. In the FIGS. 13 to18, one electron-emitting portion alone is shown.

[Step-A0]

A conductive material layer composed, for example, of polysilicon for acathode electrode is formed on a supporting member 10 made, for example,of a glass substrate by a plasma-enhanced CVD method. Then, theconductive material layer for a cathode electrode is patterned by alithograph method and a dry etching method, to form the cathodeelectrode 11 having a stripe form. Thereafter, the insulating layer 12composed of SiO₂ is formed on the entire surface by a CVD method.

[Step-A1]

Then, the conductive material layer (for example, TiN layer) for a gateelectrode is formed on the insulating layer 12 by a sputtering method.Then, the conductive material layer for a gate electrode is patterned bya lithograph method and a dry etching method, to form the stripe-shapedgate electrode 13. The cathode electrode 11 in the form of a stripeextends in a direction rightward and leftward to the paper surface ofthe drawing and the gate electrode 13 in the form of a stripe extends ina direction perpendicular to the paper surface of the drawing.

The gate electrode 13 can be formed by a known thin film forming methodsuch as a PVD method including a vacuum vapor deposition method and thelike, a CVD method, a plating method including an electroplating methodand an electroless plating method, a screen printing method, a laserabrasion method, a sol-gel method, a lift-off method and the like, or acombination of one of them with an etching method as required. Forexample, a stripe-shaped gate electrode can be directly formed when ascreen-printing method or a plating method is employed.

(Step-A2]

Then, a resist layer is formed again, and the first opening portion 14Ais formed through the gate electrode 13 by etching, and further, thesecond opening portion 14B is formed through the insulating layer byetching. The cathode electrode 11 is exposed in the bottom portion ofthe second opening portion 14B, and then, the resist layer is removed.In the above manner, a structure shown in FIG. 13(A) can be obtained.

[Step-A3]

As shown in FIG. 13(B), a peeling-off layer 17A is then formed on theinsulating layer 12 and the gate electrode 13 by oblique vapordeposition of nickel (Ni) while the supporting member 10 is turned. Inthis case, the incidence angle of vaporized particles relative to thenormal of the supporting member 10 is set at a sufficiently large angle(for example, an incidence angle of 65° to 85°), whereby the peeling-offlayer 17A can be formed on the gate electrode 13 and the insulatinglayer 12 almost without depositing any nickel in the bottom portion ofthe second opening portion 14B. The peeling-off layer 17A extends fromthe opening edge portion of the first opening portion 14A like eaves,whereby the diameter of the first opening portion 14A is substantiallydecreased.

[Step-A4]

Then, an electrically conductive material such as molybdenum (Mo) isdeposited on the entire surface by vertical vapor deposition (incidenceangle 3° to 10°). During the above vapor deposition, as shown in FIG.14(A), as the conductive material layer 17B having an overhanging formgrows on the peeling-off layer 17A, the substantial diameter of thefirst opening portion 14A is gradually decreased, and the vaporizedparticles which contribute to the deposition in the bottom portion ofthe second opening portion 14B gradually come to be limited to particleswhich pass the central region of the first opening portion 14A. As aresult, a circular-cone-shaped deposit is formed on the bottom portionof the second opening portion 14B, and the circular-cone-shaped depositconstitutes the electron-emitting portion 15.

[Step-A5]

Then, the peeling-off layer 17A is peeled off from the surfaces of thegate electrode 13 and the insulating layer 12 by a lift-off method, andthe conductive material layer 17B above the gate electrode 13 and theinsulating layer 12 are selectively removed. In this manner, the cathodepanel having a plurality of the Spindt-type field emission devices canbe obtained.

[Plane-Type Field Emission Device (No. 1)]

The plane-type field emission device comprises:

(a) cathode electrode 11 being formed on a supporting member 10 andextending in first direction,

(b) an insulating layer 12 formed on the supporting member 10 and thecathode electrode 11,

(c) a gate electrode 13 being formed on the insulating layer 12 andextending in a second direction different from the first direction,

(d) a first opening portion 14A formed through the gate electrode 13 anda second opening portion 14B being formed through the insulating layer12 and communicating with the first opening portion 14A,

(e) a flat electron-emitting portion 15A formed on the cathode electrode11 positioned in the bottom portion of the second opening portion 14B,and has a structure in which electrons are emitted from theelectron-emitting portion 15A exposed in the bottom portion of thesecond opening portion 14B.

An electron-emitting portion 15A comprises a matrix 18 and acarbon-nanotube structure (specifically, a carbon-nanotube 19) embeddedin the matrix 18 in a state where the top portion of the carbon-nanotubestructure is projected, and the matrix 18 is formed from an electricallyconductive metal oxide (specifically, indium-tin oxide, ITO).

The production method of the field emission device will be explainedwith reference to FIGS. 15(A), 15(B), 16(A) and 16(B), hereinafter.

[Step-B0]

First, a stripe-shaped cathode electrode 11 made of an approximately 0.2μm thick chromium (Cr) layer is formed on a supporting member 10 made,for example, of a glass substrate, for example, by a sputtering methodand an etching technique.

[Step-B1]

Then, a metal compound solution, consisting of an organic acid metalcompound, in which the carbon-nanotube structure is dispersed is appliedonto the cathode electrode 11, for example, by a spray method.Specifically, a metal compound solution shown in Table 3 is used. In themetal compound solution, the organic tin compound and the organic indiumcompound are in a state where they are dissolved in an acid (forexample, hydrochloric acid, nitric acid or sulfuric acid). Thecarbon-nanotube is produced by an arc discharge method and has anaverage diameter of 30 nm and an average length of 1 μm. In theapplication, the supporting member 10 is heated to 70-150° C.Atmospheric atmosphere is employed as an application atmosphere. Afterthe application, the supporting member is heated for 5 to 30 minutes tofully evaporate butyl acetate off. When the supporting member is heatedduring the application as described above, the applied solution beginsto dry before the carbon-nanotube is self-leveled toward the horizontaldirection of the surface of the cathode electrode. As a result, thecarbon-nanotube can be arranged on the surface of the cathode electrodein a state where the carbon-nanotube is not in a level position. Thatis, the carbon-nanotube can be aligned in the direction in which the topportion of the carbon-nanotube faces the anode electrode, in otherwords, the carbon-nanotube comes close to the normal direction of thesupporting member. The metal compound solution having a compositionshown in Table 3 may be prepared beforehand, or a metal compoundsolution containing no carbon-nanotube may be prepared beforehand andthe carbon-nanotube and the metal compound solution may be mixed beforethe application. For improving dispersibility of the carbon-nanotube,ultrasonic waves may be applied when the metal compound solution isprepared. TABLE 3 Organic tin compound and 0.1-10 parts by weightorganic indium compound Dispersing agent (sodium  0.1-5 parts by weightdodecylsulfate) Carbon-nanotube 0.1-20 parts by weight Butyl acetateBalance

When a solution of an organic tin compound dissolved in an acid is usedas an organic acid metal compound solution, tin oxide is obtained as amatrix. When a solution of an organic indium compound dissolved in anacid is used, indium oxide is obtained as a matrix. When a solution ofan organic zinc compound dissolved in an acid is used, zinc oxide isobtained as a matrix. When a solution of an organic antimony compounddissolved in an acid is used, antimony oxide is obtained as a matrix.When a solution of an organic antimony compound and an organic tincompound dissolved in an acid is used, antimony-tin oxide is obtained asa matrix. Further, when an organic tin compound is used as an organicmetal compound solution, tin oxide is obtained as a matrix. When anorganic indium compound is used, indium oxide is obtained as a matrix.When an organic zinc compound is used, zinc oxide is obtained as amatrix. When an organic antimony compound is used, antimony oxide isobtained as a matrix. When an organic antimony compound and an organictin compound are used, antimony-tin oxide is obtained as a matrix.Alternatively, a solution of metal chloride (for example, tin chlorideor indium chloride) may be used.

After the metal compound solution is dried, salient convexo-concaveshapes may be formed in the surface of the metal compound layer in somecases. In such cases, it is desirable to apply the metal compoundsolution again on the metal compound layer without heating thesupporting member.

[Step-B2]

Then, the metal compound composed of the organic acid metal compound isfired, to give an electron-emitting portion 15A having thecarbon-nanotubes 19 fixed onto the surface of the cathode electrode 11with the matrix 18 (which is specifically a metal oxide, and morespecifically, ITO) containing metal atoms (specifically, In and Sn)derived from the organic acid metal compound. The firing is carried outin an atmospheric atmosphere at 350° C. for 20 minutes. Thethus-obtained matrix 18 had a volume resistivity of 5×10⁻⁷Ω·m. When theorganic acid metal compound is used as a starting material, the matrix18 made of ITO can be formed at a low firing temperature of as low as350° C. The organic acid metal compound solution may be replaced with anorganic metal compound solution. When a solution of metal chloride (forexample, tin chloride and indium chloride) is used, the matrix 18 madeof ITO is formed while the tin chloride and indium chloride are oxidizedby the firing.

[Step-B3]

Then, a resist layer is formed on the entire surface, and the circularresist layer having a diameter, for example, of 10 μm is retained abovea desired region of the cathode electrode 11. The matrix 18 is etchedwith hydrochloric acid having a temperature of 10 to 60° C. for 1 to 30minutes, to remove an unnecessary portion of the electron-emittingportion. Further, when the carbon-nanotubes still remain in a regiondifferent from the desired region, the carbon-nanotubes are etched by anoxygen plasma etching treatment under a condition shown in Table 4. Abias power may be 0 W, i.e., direct current, while it is desirable toapply the bias power. The supporting member may be heated, for example,to approximately 80° C. TABLE 4 Apparatus to be used RIE apparatus Gasto be introduced Gas containing oxygen Plasma exciting power 500 W Biaspower 0-150 W Treatment time period at least 10 seconds

Alternatively, the carbon-nanotubes can be etched by a wet etchingtreatment under a condition shown in Table 5. TABLE 5 Solution to beused KMnO₄ Temperature 20-120 (C. Treatment time period 10 seconds-20minutes

Then, the resist layer is removed, whereby a structure shown in FIG.15(A) can be obtained. It is not necessarily required to retain acircular electron-emitting portion 15A having a diameter of 10 μm. Forexample, the electron-emitting portion may be retained on the cathodeelectrode 11.

The process may be carried out in the order of [Step-B1], [Step-B3] and[Step-B2].

[Step-B4]

An insulating layer 12 is formed on the electron-emitting portion 15A,the supporting member 10 and the cathode electrode 11. Specifically, anapproximately 1 μm thick insulating layer 12 is formed on the entiresurface by a CVD method using, for example, tetraethoxysilane (TEOS) asa source gas.

[Step-B5]

Then, a stripe-shaped gate electrode 13 is formed on the insulatinglayer 12. Further, a mask layer 118 is formed on the insulating layer 12and the gate electrode 13, then, a first opening portion 14A is formedthrough the gate electrode 13, a second opening portion 14Bcommunicating with the first opening portion 14A formed through the gateelectrode 13 is formed through the insulating layer 12 (see FIG. 15(B)).When the matrix 18 is made of a metal oxide, for example, ITO, theinsulating layer 12 can be etched without etching the matrix 18. Thatis, the etching selective ratio between the insulating layer 12 and thematrix 18 is approximately infinite. The carbon-nanotubes 19 aretherefore not damaged when the insulating layer 12 is etched.

[Step-B6]

Then, preferably, part of the matrix 18 is removed under a conditionshown in Table 6, to obtain the carbon-nanotubes 19 in a state where topportions thereof are projected from the matrix 18. In this manner, theelectron-emitting portion 15A having a structure shown in FIG. 16(A) canbe obtained. TABLE 6 Etching solution Hydrochloric acid Etching timeperiod 10 seconds-30 seconds Etching temperature 10-60° C.

Some or all of the carbon-nanotubes 19 may change in their surface statedue to the etching of the matrix 18 (for example, oxygen atoms or oxygenmolecules or fluorine atoms are adsorbed to their surfaces), and thecarbon-nanotubes 19 are deactivated with respect of electric fieldemission in some cases. Therefore, it is preferred to subject theelectron-emitting portion 15A to a plasma treatment in a hydrogen gasatmosphere. By the plasma treatment, the electron-emitting portion 15Ais activated, and the efficiency of emission of electrons from theelectron-emitting portion 15A is further improved. Table 7 shows anexample of a plasma treatment condition. TABLE 7 Gas to be used H₂ = 100sccm Source power 1000 W Power to be applied to supporting 50 V memberReaction pressure 0.1 Pa Supporting member temperature 300° C.

Then, for releasing gas from the carbon-nanotubes 19, a heatingtreatment or various plasma treatments may be carried out. For allowinga substance to be adsorbed to the surfaces of the carbon-nanotubes 19,the carbon-nanotubes 19 may be exposed to a gas containing the substancewhose adsorption is desirable. For purifying the carbon-nanotubes 19, anoxygen plasma treatment or a fluorine plasma treatment may be carriedout.

[Step-B7]

Then, the side wall surfaces of the second opening portion 14B formedthrough the insulating layer 12 are allowed to recede by isotropicetching, which is preferred from the viewpoint of exposing the openingend portion of the gate electrode 13. The isotropic etching can becarried out by dry etching using radicals as main etching species likechemical dry etching, or by wet etching using an etching solution. As anetching solution, for example, a mixture containing a 49% hydrofluoricacid aqueous solution and pure water in a hydrofluoric acid aqueoussolution: pure water volume ratio of 1:100 can be used. Then, the masklayer 118 is removed, whereby a field emission device shown in FIG.16(B) is completed.

The above process can be carried out in the order of [Step-B5],[Step-B7] and [Step-B6].

(Plane-Type Field Emission Device (No. 2)]

FIG. 17(A) shows a schematic partial cross-sectional view of aplane-type field emission device. The plane-type field emission devicecomprises a cathode electrode 11 formed on a supporting member 10 made,for example, of glass, an insulating layer 12 formed on the supportingmember 10 and the cathode electrode 11, a gate electrode 13 formed onthe insulating layer 12, an opening portion 14 formed through the gateelectrode 13 and the insulating layer 12 (a first opening portion formedthrough the gate electrode 13 and a second opening portion being formedthrough the insulating layer 12 and communicating with the first openingportion), and a flat electron-emitting portion (electron-emitting layer15B) formed on that portion of the cathode electrode 11 which ispositioned in the bottom portion of the opening portion 14. Theelectron-emitting layer 15B is formed on the stripe-shaped cathodeelectrode 11 extending in the direction perpendicular to the papersurface of the drawing. Further, the gate electrode 13 is extendingleftward and rightward on the paper surface of the drawing. The cathodeelectrode 11 and the gate electrode 13 are made of chromium.Specifically, the electron-emitting layer 15B is constituted of a thinlayer made of a graphite powder. In the plane-type field emission deviceshown in FIG. 17(A), the electron-emitting layer 15B is formed on theentire region of the surface of the cathode electrode 11, while theplane-type field emission device shall not be limited to such astructure, and the point is that the electron-emitting layer 15B isformed at least in the bottom portion of the opening portion 14.

[Flat-Type Field Emission Device]

FIG. 17(B) shows a schematic partial cross-sectional view of a flat-typefield emission device. The flat-type field emission device comprises astripe-shaped cathode electrode 11 formed on a supporting member 10made, for example, of glass, an insulating layer 12 formed on thesupporting member 10 and the cathode electrode 11, a stripe-shaped gateelectrode 13 formed on the insulating layer 12, and first and secondopening portions (opening portion 14) formed through the gate electrode13 and the insulating layer 12. The cathode electrode 11 is exposed inthe bottom portion of the opening portion 14. The cathode electrode 11is extending in the direction perpendicular to the paper surface of thedrawing, and the gate electrode 13 is extending leftward and rightwardon the paper surface of the drawing. The cathode electrode 11 and thegate electrode 13 are made of chromium (Cr), and the insulating layer 12is made of SiO₂. That portion of the above cathode electrode 11 which isexposed in the bottom portion of the opening portion 14 corresponds toan electron-emitting portion 15C.

While the present invention has been explained on the basis of preferredExamples, the present invention shall not be limited thereto. Theconstitutions and structures explained with regard to the anode panel,the cathode panels, the displays and the field emission devices inExamples are given as examples and may be modified as required. Themanufacturing method explained with regard to the anode panel, thecathode panels, the displays and the field emission devices are given asexamples and may be modified as required. Further, the various materialsused in the manufacture of the anode panel and the cathode panels arealso given as examples and may be modified as required. With regard tothe display, color displays are explained as examples, while the displaymay be a monochromatic display.

The anode electrode may be an anode electrode having a form in which theeffective field is covered with one sheet-shaped electrically conductivematerial or may be an anode electrode having a form in which anodeelectrode units each of which corresponds to one or a plurality ofelectron-emitting portions or one or a plurality of pixels are gathered.When the anode electrode has the former constitution, the anodeelectrode can be connected to the anode-electrode control circuit. Whenthe anode electrode has the latter constitution, for example, each anodeelectrode unit can be connected to the anode-electrode control circuit.

In the field emission device, there have been mostly explainedembodiments in which one electron-emitting portion corresponds to oneopening portion, while there may be employed an embodiment in which aplurality of electron-emitting portions correspond to one openingportion or one electron-emitting portion corresponds to a plurality ofopening portions, depending upon the structure of the field emissiondevice. Alternatively, there may be also employed an embodiment in whicha plurality of first opening portions are formed through a gateelectrode, a plurality of second opening portions communicating with aplurality of the first opening portion are formed through an insulatinglayer, and one or a plurality of electron-emitting portions are formed.

The gate electrode can be formed so as to have a form in which theeffective field is covered with one sheet of an electrically conductivematerial (having a first opening portion). In this case, a positivevoltage (e.g., 160V ) is applied to the gate electrode. And, a switchingelement constituted, for example, of TFT is provided between the cathodeelectrode constituting a pixel and the cathode-electrode controlcircuit, and the voltage application state to the electron-emittingportion constituting the pixel is controlled by the operation of theabove switching element, to control the light emission state of thepixel.

Alternatively, the cathode electrode can be formed so as to have a formin which the effective filed is covered with one sheet of anelectrically conductive material. In this case, a voltage (e.g., 0V ) isapplied to the cathode electrode. And, a switching element constituted,for example, of TFT is provided between the electron-emitting portionconstituting a pixel and the gate-electrode control circuit, and thevoltage application state to the gate electrode constituting the pixelis controlled by the operation of the switching element, to control thelight emission state of the pixel.

The field emission device in the present invention may have aconstitution in which a second insulating layer 52 is further formed onthe gate electrode 13 and the insulating layer 12, and a focus electrode53 is formed on the second insulating layer 52. FIG. 18 shows aschematic partial end view of the thus-constituted field emissiondevice. The second insulating layer 52 has a third opening portion 54communicating with the first opening portion 14A. The focus electrode 53may be formed as follows. For example, in [Step-A2], the gate electrode13 in the form of a stripe is formed on the insulating layer 12; thesecond insulating layer 52 is formed; a patterned focus electrode 53 isformed on the second insulating layer 52; the third opening portion 54is formed in the focus electrode 53 and the second insulating layer 52;and further, the first opening portion 14A is formed in the gateelectrode 13. The focus electrode may be a focus electrode having a formin which focus electrode units, each of which corresponds to one or aplurality of electron-emitting portions or one or a plurality of pixels,are gathered, or may be a focus electrode having a form in which theeffective field is covered with a sheet of an electrically conductivematerial, depending upon the patterning of the focus electrode. FIG. 18shows a Spindt-type field emission device, however, the focus electrodecan be also applied to another type of the field emission device.

The focus electrode may be replaced with a focus electrode which will beexplained hereinafter. That is, one example of the focus electrode canbe formed by forming an insulation film made, for example, of SiO₂ oneach surface of a metal sheet made, for example, of 42% Ni—Fe alloyhaving a thickness of several tens micrometers, and then forming openingportions in regions corresponding to pixels by punching or etching. And,the cathode panel, the metal sheet and the anode panel are stacked, aframe is arranged in their circumferential portions of the two panels,and a heat treatment is carried out to bond the insulation film formedon one surface of the metal sheet and the insulating layer 12 and tobond the insulation layer formed on the other surface of the metal sheetand the anode panel, whereby these members are integrated, followed byevacuating and sealing. In this manner, the display can be alsocompleted.

Further, the electron-emitting region can be also constituted of devicesgenerally called surface-conduction-type field emission devices. Thesurface-conduction-type field emission device comprises a supportingmember made of, for example, glass and pairs of electrodes formed on thesupporting member in the form of a matrix, the electrodes being made ofan electrically conductive material such as tin oxide (SnO₂), gold (Au),indium oxide (In₂O₃)/tin oxide (SnO₂), carbon or palladium oxide (PdO)and having a fine area and a pair of the electrodes being arranged atconstant intervals (gaps). A carbon thin film is formed on eachelectrode. A row-direction wiring is connected to one electrode of apair of the electrodes, and a column-direction wiring is connected tothe other electrode of a pair of the electrodes. When a voltage isapplied to a pair of the electrodes, an electric field is applied to thecarbon thin films opposed to each other through the gap, and electronsare emitted from the carbon thin film. Such electrons are allowed tocollide with a phosphor layer on an anode panel to excite the phosphorlayer, whereby a desired image can be obtained.

In Examples, the displays are so-called three-electrode type displays,while the display can be a so-called two-electrode type display. FIGS.19 and 20 show schematic partial end views of two-electrode typedisplays. FIGS. 19 and 20 correspond to end views taken along arrows A-Ain FIG. 3. Spacer holders 30 and 30A have substantially the samestructures and constitutions as those in Examples 1 to 6, and they canbe formed substantially in the same manner as in Examples 1 to 6. Theexample shown in FIG. 19 is a variant of the display explained inExample 1, and the example shown in FIG. 20 is a variant of the displayexplained in Example 2.

The field emission device in the above cold cathode field emissiondisplay comprises a cathode electrode 11 formed on a supporting member10 and an electron-emitting portion 15A constituted of carbon nano-tubes19 formed on the cathode electrode 11. An anode electrode 24Aconstituting the anode panel AP has the form of a stripe. The projectionimage of the stripe-shaped cathode electrode 11 and the projection imageof the stripe-shaped anode electrode 24A cross each other at rightangles. Specifically, the cathode electrode 11 extends in the directionperpendicular to the paper surface of the FIGS. 19 and 20, and the anodeelectrode 24A extends leftward and rightward on the paper surface of theFIGS. 19 and 20. In a cathode panel CP in the above display, a number ofelectron emitting regions EA, each of which is constituted of aplurality of the above field emission devices, are formed on theeffective field in the form of a two-dimensional matrix.

One (each) pixel is constituted of a cathode electrode 11 having theform of a stripe on the cathode panel side, an electron emitting portion15A formed thereon and phosphor layers 23 that are aligned in theeffective field of an anode panel so as to be opposed to the electronemitting portion 15A. In the effective field, such pixels are arrangedin the order of hundreds of thousand to several millions.

A spacer 31 held with spacer holders 30 and 30A is arranged between thecathode panel CP and the anode panel AP for maintaining a constantdistance between these two panels.

In the above display, electrons are emitted from the electron-emittingportion 15A on the basis of a quantum tunnel effect under an electricfield formed with the anode electrode 24A, and the electrons areattracted toward the anode electrode 24A to collide with the luminescentlayer 23. That is, the cold cathode field emission display is driven bya so-called simple matrix method in which electrons are emitted from theelectron-emitting portion 15A positioned in a region where theprojection image of the anode electrode 24A and the projection image ofthe cathode electrode 11 overlap each other (anode electrode/cathodeelectrode overlap region). Specifically, a relatively negative voltageis applied to the cathode electrode 11 from the cathode-electrodedriving circuit 40 and a relatively positive voltage is applied to theanode electrode 24A from the anode-electrode driving circuit 42. As aresult, electrons are selectively released into a vacuum space from thecarbon nano-tubes 19 constituting the electron-emitting portion 15Apositioned in the anode electrode/cathode electrode overlap region of acathode electrode 11 selected as a column and an anode electrode 24Aselected as a row (or a row-selected cathode electrode 11 selected as arow and an anode electrode 24A selected as a column), and the electronsare attracted toward the anode electrode 24A to collide with theluminescent layer 23 constituting the anode panel AP. The electronsexcite the luminescent layer 23 to emit light.

The structures of the displays explained in Examples 3 to 6 can beapplied to the above two-electrode type display.

It is not necessarily required to insert the spacer between a pair ofspacer holders, and for example, the spacer holders may be arranged inthe form of a straight line or in the form of a cross-stitch. FIGS.21(A) to 21(C) show schematic partial plan views of examples in which aplurality of projected spacer holders 230 are arranged on a straightline, and FIG. 21(D) shows a schematic partial plan view of an examplein which a plurality of projected spacer holders 230 are arranged in theform of a cross-stitch (specifically, a plurality of the spacer holders230 are arranged such that they are shifted in the direction at rightangles with the extending direction of the spacer). Concerningdimensions of the spacer holders 230, the spacer holders 230 have, forexample, a diameter of 10 to 100 μm and a height of 30 to 100 μmalthough they are dependent upon the height and thickness of the spacerand the width of the light-absorbing layer. The spacer holders 230 canbe formed, for example, by printing a photosensitive polyimide resinaccording to a screen printing method and then carrying out exposure anddevelopment. When the spacer is temporarily held with thethus-structured spacer holders 230, the spacer is temporarily held withthe spacer in a state in which it meanders. The spacer holders 230 maybe formed at equal intervals as shown in FIG. 21(A) or 21(D), the spacerholders 230 may be formed at different intervals as shown in FIG. 21(B),or the spacer 31 may be temporarily held with three spacer holders 230as shown in FIG. 21(C). While cylindrical spacer holders 230 are shownin the drawings, the outer form of the spacer holders 230 shall not belimited thereto, and the spacer holders 230 may have the outer form of aprism or a rivet (form of a cylinder with a step).

In the present invention, the spacer is fixed to the first paneleffective field and/or the second panel effective field with thelow-melting-point metal material layer, so that the tilting or fallingof the spacer can be reliably prevented in the process of manufacturinga flat-type display. Further, the present invention is free from suchproblems wherein a gas is released from a material fixing the spacer, orwhere a material fixing the spacer is thermally deteriorated, in variousheat-treatment steps of the process of manufacturing a flat-typedisplay, so that there can be easily manufactured flat-type displayshaving a pressure tight structure and having an easy and simplestructure. As a result, the yield of assembly of flat-type displays canbe improved, and further, the cost for manufacturing flat-type displayscan be decreased. Furthermore, the form accuracy and processing accuracyof spacers can be decreased, or the tolerance of thickness of thespacers can be increased, so that the cost for producing the spacers canbe decreased. Moreover, the flat-type displays can be easily assembledand manufactured, so that the time period for manufacturing flat-typedisplays can be decreased, and a part of each spacer can be groundedsimultaneously with fixing the spacers to the first panel effectivefield and/or the second panel effective field.

Further, the space holders for temporarily holding the spacer areformed, so that the spacer can be reliably and perpendicularly held andtemporarily held with the spacer holders. Further, when the first paneland the second panel are bonded to each other in their circumferentialportions with the bonding layer made from the low-melting-point metalmaterials, the vacuum degree of the vacuum space can be improved, andthe high vacuum degree can be maintained for a long period of time, sothat flat-type displays are improved in reliability.

1. A flat-type display comprising; a first panel and a second panelwhich are bonded to each other in their circumferential portions andhaving a space between the first panel and the second panel, the spacebeing in a vacuum state, in which a spacer is disposed between a firstpanel effective field and a second panel effective field that work as adisplay portion, and, said spacer is fixed to the first panel effectivefield and/or the second panel effective field with a low-melting-pointmetal material layer.
 2. The flat-type display according to claim 1, inwhich the spacer is formed of ceramics or glass.
 3. The flat-typedisplay according to claim 1, in which the first panel and the secondpanel are bonded to each other in their circumferential portions througha bonding layer made of frit glass.
 4. The flat-type display accordingto claim 1, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of a low-melting-point metal material.
 5. The flat-type displayaccording to claim 1, in which the flat-type display is a cold cathodefield emission display, the first panel is an anode panel in which ananode electrode and a phosphor layer are formed, and, the second panelis a cathode panel in which a plurality of cold cathode field emissiondevices are formed.
 6. The flat-type display according to claim 1, inwhich a plurality of spacer holders for temporarily holding the spacerare formed in the first panel effective field and/or the second paneleffective field.
 7. The flat-type display according to claim 6, in whichthe spacer is formed of ceramics or glass.
 8. The flat-type displayaccording to claim 6, in which the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of frit glass.
 9. The flat-type display according to claim 6,in which the first panel and the second panel are bonded to each otherin their circumferential portions through a bonding layer made of alow-melting-point metal material.
 10. The flat-type display according toclaim 6, in which the flat-type display is a cold cathode field emissiondisplay, the first panel is an anode panel in which an anode electrodeand a phosphor layer are formed, and, the second panel is a cathodepanel in which a plurality of cold cathode field emission devices areformed.
 11. A method for manufacturing a flat-type display, saidflat-type display comprising a first panel and a second panel which arebonded to each other in their circumferential portions and having aspace between the first panel and the second panel, the space being in avacuum state, a spacer being disposed between a first panel effectivefield and a second panel effective field that work as a display portion,said method comprising; (A) arranging a spacer with a low-melting-pointmetal material layer formed on one top surface thereof, on the firstpanel effective field, then, (B) heating the low-melting-point metalmaterial layer to melt the same and thereby fixing said spacer to thefirst panel effective field, and then, (C) placing the second panel onthe other top surface of the spacer, bonding the first panel and thesecond panel to each other in their circumferential portions, andvacuuming the space sandwiched between the first panel and the secondpanel.
 12. The method for manufacturing a flat-type display according toclaim 11, in which the spacer is formed of ceramics or glass.
 13. Themethod for manufacturing a flat-type display according to claim 11, inwhich the first panel and the second panel are bonded to each other intheir circumferential portions through a bonding layer made of fritglass.
 14. The method for manufacturing a flat-type display according toclaim 11, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of a low-melting-point metal material.
 15. The method formanufacturing a flat-type display according to claim 11, in which theflat-type display is a cold cathode field emission display, the firstpanel is an anode panel in which an anode electrode and a phosphor layerare formed, and, the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed.
 16. Themethod for manufacturing a flat-type display according to claim 11, inwhich the flat-type display is a cold cathode field emission display,the first panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and, the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed. 17.The method for manufacturing a flat-type display according to claim 11,in which a second low-melting-point metal material layer is formed onthe other top surface of said spacer, and, the second low-melting-pointmetal material layer is melted together when the first panel and thesecond panel are bonded to each other in their circumferential portionsin said step (C), and said spacer is thereby fixed to the second paneleffective field.
 18. The method for manufacturing a flat-type displayaccording to claim 17, in which the spacer is formed of ceramics orglass.
 19. The method for manufacturing a flat-type display according toclaim 17, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of frit glass.
 20. The method for manufacturing a flat-type displayaccording to claim 17, in which the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of a low-melting-point metal material.
 21. The method formanufacturing a flat-type display according to claim 17, in which theflat-type display is a cold cathode field emission display, the firstpanel is an anode panel in which an anode electrode and a phosphor layerare formed, and, the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed.
 22. Themethod for manufacturing a flat-type display according to claim 17, inwhich the flat-type display is a cold cathode field emission display,the first panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and, the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed. 23.The method for manufacturing a flat-type display according to claim 11,in which a plurality of spacer holders for temporarily holding thespacer are formed in the first panel effective field and/or the secondpanel effective field.
 24. The method for manufacturing a flat-typedisplay according to claim 23, in which the spacer is formed of ceramicsor glass.
 25. The method for manufacturing a flat-type display accordingto claim 23, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of frit glass.
 26. The method for manufacturing a flat-type displayaccording to claim 23, in which the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of a low-melting-point metal material.
 27. The method formanufacturing a flat-type display according to claim 23, in which theflat-type display is a cold cathode field emission display, the firstpanel is an anode panel in which an anode electrode and a phosphor layerare formed, and, the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed.
 28. Themethod for manufacturing a flat-type display according to claim 23, inwhich the flat-type display is a cold cathode field emission display,the first panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and, the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed.
 29. Amethod for manufacturing a flat-type display, said flat-type displaycomprising a first panel and a second panel which are bonded to eachother in their circumferential portions and having a space between thefirst panel and the second panel, the space being in a vacuum state, aspacer being disposed between a first panel effective field and a secondpanel effective field that work as a display portion, said methodcomprising; (A) providing the first panel in which a low-melting-pointmetal material layer is formed in a portion where the spacer is to befixed in the first panel effective field, (B) arranging the spacer onsaid low-melting-point metal material layer, heating thelow-melting-point metal material layer to melt the same, and therebyfixing said spacer to the first panel effective field, and then, (C)placing the second panel on the other top surface of the spacer, bondingthe first panel and the second panel in their circumferential portionsand vacuuming the space sandwiched between the first panel and thesecond panel.
 30. The method for manufacturing a flat-type displayaccording to claim 29, in which the spacer is formed of ceramics orglass.
 31. The method for manufacturing a flat-type display according toclaim 29, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of frit glass.
 32. The method for manufacturing a flat-type displayaccording to claim 29, in which the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of a low-melting-point metal material.
 33. The method formanufacturing a flat-type display according to claim 29, in which theflat-type display is a cold cathode field emission display, the firstpanel is an anode panel in which an anode electrode and a phosphor layerare formed, and, the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed.
 34. Themethod for manufacturing a flat-type display according to claim 29, inwhich the flat-type display is a cold cathode field emission display,the first panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and, the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed. 35.The method for manufacturing a flat-type display according to claim 29,in which a second low-melting-point metal material layer is formed on aportion where the spacer is to be fixed in the second panel effectivefield, and, the second low-melting-point metal material layer is meltedwhen the first panel and the second panel are bonded in theircircumferential portions in said step (C), and thereby the spacer isfixed to the second panel effective field.
 36. The method formanufacturing a flat-type display according to claim 35, in which thespacer is formed of ceramics or glass.
 37. The method for manufacturinga flat-type display according to claim 35, in which the first panel andthe second panel are bonded to each other in their circumferentialportions through a bonding layer made of frit glass.
 38. The method formanufacturing a flat-type display according to claim 35, in which thefirst panel and the second panel are bonded to each other in theircircumferential portions through a bonding layer made of alow-melting-point metal material.
 39. The method for manufacturing aflat-type display according to claim 35, in which the flat-type displayis a cold cathode field emission display, the first panel is an anodepanel in which an anode electrode and a phosphor layer are formed, and,the second panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed.
 40. The method for manufacturing aflat-type display according to claim 35, in which the flat-type displayis a cold cathode field emission display, the first panel is a cathodepanel in which a plurality of cold cathode field emission devices areformed, and, the second panel is an anode panel in which an anodeelectrode and a phosphor layer are formed.
 41. The method formanufacturing a flat-type display according to claim 29, in which aplurality of the spacer holders for temporarily holding the spacer areformed in the first panel effective field and/or the second paneleffective field.
 42. The method for manufacturing a flat-type displayaccording to claim 41, in which the spacer is formed of ceramics orglass.
 43. The method for manufacturing a flat-type display according toclaim 41, in which the first panel and the second panel are bonded toeach other in their circumferential portions through a bonding layermade of frit glass.
 44. The method for manufacturing a flat-type displayaccording to claim 41, in which the first panel and the second panel arebonded to each other in their circumferential portions through a bondinglayer made of a low-melting-point metal material.
 45. The method formanufacturing a flat-type display according to claim 41, in which theflat-type display is a cold cathode field emission display, the firstpanel is an anode panel in which an anode electrode and a phosphor layerare formed, and, the second panel is a cathode panel in which aplurality of cold cathode field emission devices are formed.
 46. Themethod for manufacturing a flat-type display according to claim 41, inwhich the flat-type display is a cold cathode field emission display,the first panel is a cathode panel in which a plurality of cold cathodefield emission devices are formed, and, the second panel is an anodepanel in which an anode electrode and a phosphor layer are formed.